How to get threads in a yeast dough?

Damn, that looks good. I've never made this particular type of bread before, but here are some things that I do know which might help:

Butter is (roughly) 10% water and 90% fat, while lard is 100% fat. So if you substitute one for the other, you should adjust the amount of water in the recipe accordingly. The flavor will be a little different, but I bet either one would work.

I would not assume AP flour. In fact, I'd assume high-gluten bread flour. The gluten is what creates those fibers. It's the fat that keeps it tender.

This looks very similar to a brioche, so you might want to look at brioche recipes to learn some of the principles. One thing that most of them will tell you is to to knead the dough to develop the gluten fibers, and then add the butter. This I think is the key. I know that fat can keep gluten molecules from sticking together into strands, so if you add the fat later, you should wind up with strands of gluten surrounded by fat.

I make braided bread every week using an oatmeal buns recipe. It, too, doesn't like to be overworked. It's best with maybe 5 minutes of kneading.

I don't actually think it is the ingredients that create the threads. It may be the braiding. Here are some of my key tips to successful bread: ALWAYS use a thermometer!Use a pattern to hand kneading like this: Fold the top over with your left hand, gently press it in with your right palm, turn the dough a quarter turn clockwise, repeat. Treat it like a baby, not an enemy, lol.

Identifying when dough is "doubled" is very important. To see if the dough is doubled after the first rise, stick 2 fingers into the dough. If it "sighs" and slightly deflates, it is doubled. Deflate completely by gently pressing dough down, not punching, since that can tear the gluten strands. You don't have to squeeze every last bit of air out of it. You could knead it maybe 5 times if you like, but that isn't necessary.

Divide dough into however many strands you want to braid. Roll into ropes, gently elongating, not pulling, because that tears the strands. I sometimes do a hand-over-hand gentle squeeze down the length of the rope and then gently roll it to smooth it. If it is too tight and springy, let it rest 5 minutes and come back to it.

Roll it out on a floured board, coating each rope in a dusting of flour, which I think creates some of the separation of the strands you are looking for. Lay the ropes side-by-side. Then start in the middle and braid to one end, turn it and braid to the other end, so that in the lifting of strands you don't break the ropes. Seal the ends together by pinching.

I slather it with 1 beaten egg with a teaspoon of water beaten into it. My young daughter accidentally discovered that the texture and moistness is very positively affected by repeated brushings till the whole egg is used up on two loaves. I don't know why. You can't argue with success.

By the way, I use active dry yeast, not quick rise. Better flavor. So the following timing is based on that. I preheat my oven for 5 minutes to 200 F and turn it off. I put the braided and brushed loaves into the oven on the greased cookie cookie sheet maybe 15 minutes. I remove the loaves and set them on the stove while the oven preheats to 375 F. I bake them for about 25 minutes, or until they are golden and I hear a hollow sound when I tap the top center of the loaf. This tapping needs to be done in the oven, or immediately upon removal from the oven, because the hot steam from the inside of the bread will soften the crust quickly. You can't tap it 5 minutes later or even a minute later. It won't sound hollow. The top crust on my recipe feels rigid at this point, but as it cools, it softens (and my bread is legendary among my crowd). Cover the bread with a kitchen towel. Five minutes later, remove from the cookie sheet to a cooling rack. Those 5 minutes allow the bread to become less fragile, and the loaves steam off the pan a little. Do remove to a cooling rack at 5 minutes rather than leave on the pan, because that steaming action will cause the bread to become soggy and lose much of its flavor. It would seem logical to put it in plastic as soon as possible to keep the moisture in, but trust me, you will completely ruin the bread if you do this. Cover the bread on the cooling rack with a kitchen towel and let it cool completely. It may take a good hour or more. Leave it under the towel till time to serve. Even all day. If you must enclose it, for transport or whatever, use a paper bag with lots of breathing room. After 3 to 12 hours, you could store it airtight. I don't know. It never lasts that long, lol.

I looked up your kind of bread on google and found this recipe.http://www.food.com/recipe/bulgarian-easter-bread-kozunak-109967

You might want to look at their method and mine and use your family's ingredients and see if you can merge them to come up with what you are looking for. Hope this helps!

The texture reminds me of two things - Italian "cakes" sold in the UK "German" supermarkets at Christmas (which are the colour in the photo), and the Lardy Cake that is made in Buckinghamshire (I mention that because you wanted to know about using lard).

The stringing in the Italian cakes seem to show that they are allowed to "rise into shape" - I am wondering if the key to the process is using two lots of dough, one of which is proved less than the other. Make a parcel of one inside the other?

I consulted my literature again before making it and could build a theory behind the whole. Gluten is built by 1) kneading (which encourages protein cross-linking) and 2) waiting. Obviously, I don't want much cross-linking for threads, I want the molecules to bind end-to-end. So in theory, I should let it rise for a very long time, and only occasionaly knead/pull in a direction to align the gluten. This is consistent with usual practice.

As was to be expected, I botched the practical part. That's why I can't confirm it empirically. It was partly my fault (I didn't reduce the amount of yeast in the recipe) and partly the global warming :P (it is unusual that my flat is over 30°C warm at easter, but that's what happened this year). My steps included:

1. preleaven yeast in milk
2. make dough without butter, let rise
3. work melted butter into dough, let rise (thank you @Mike Baranczak for the explanation, now it makes clear why the step is needed - of course, my grandma didn't know that, she puts the butter in from the beginning and then religiously disrupts the raising by kneading)
4. form and braid dough, put into pans, let rise
5. bake

With the prescribed amount of fresh yeast and the high temperature, every rising took no longer than 2 hours, and at the and the yeast was really spent and deflating in the last pan. Besides, the recipe may be too rich. The dough wasn't exactly liquid - I could tear pieces off and form them - but the braided strands joined together after 3-4 minutes. I could still see where the boundary between them should have been, but it was soft enough to be a single mass after forming, the viscosity (but not the overall texture) was something similar to "soft peaks" in eggwhite beating.

End result: Extremely tasty. Melted in the mouth. And that unmistakable childhood memory of springtime holiday - I could barely restrain myself from running out and chasing butterflies through the jasmine and lilac bushes.

But nothing even remotely resembling threads.

I found an interesting video on baking kozunak on Youtube, and it looks like it sheds some light on your questions. The "thread" aspect is emphasized as "stringiness" in the video, namely described as being "like string cheese".

1. Fat type. They use a combination of butter and lard. In this case, it looks like a 3:2 ratio of butter to lard. Also worth mentioning that they use warm ingredients -- so the butter and lard are softened/melted when incorporated into the mix. It looks like they use nearly 22% of the weight of the flour in butter/lard (125g to 575g flour). Furthermore, they use a lot of eggs. More eggs than fat (150g vs 125g).
2. How many times to let it rise? It looks like they only specifically allot time for a final proof (after shaping). That being said, I've found another recipe (that produces desired threads) that does add a 1-2 hour bulk ferment. The proof takes about 3-4 hours at 35C/95F (or until doubled), and the dough is coated in a little oil before the proof. Note that the recipe does use a poolish starter made from milk, flour, sugar and yeast. Around an hour passes before they add the starter to the main dough (it takes about half an hour for the preferment to be ready to be used -- i.e. when it doubles in size.)
3. How much should I knead? It looks like a lot of kneading. They spend about 30 minutes kneading room temperature ingredients (eggs, yogurt, sugar, salt, flour, then fat) for the main dough. This long kneading time makes sense since the dough is being kneaded with lots of fat and sugar. Then they add the preferment and continue kneading until it's incorporated (they say another 30 minutes -- and, yes, this is a long time; a different source I found mentions kneading 60-90 minutes (by hand) while the fat is added). Fruit zests are added last, then the dough is mixed and kneaded until it passes windowpane. Raisins are kneaded/folded in by hand at the end right before shaping.
4. Optimal oven temperature? Not sure about optimal, but they do 165-170C (329-338F) with no fan (conventional) for 40 minutes. They add a little water (50ml) to the oven for moisture (for a softer crust I assume). The final internal temperature of the bread should be at least 95 C (203 F).

Other things to point out:

• Braiding appears to be important for getting threads. Note how the dough is formed into balls and braided
• The recipe uses a surprisingly small amount of salt (at least to me). In baker's percentage it's a little less than 0.2%. Not sure if this is relevant for creating threads, but I'd imagine some impact since salt tightens gluten.
• Entire process takes about 6.5 hours from start to finish (according to the video)
• The flour they use (Wheat Flour Type 500) is quite low protein: only 10%. So we are talking a protein content lower than many all-purpose flours. This probably explains why so much kneading is done.
• As with pretty much any bread, let it cool for at least an hour before cutting/breaking.

Another user mentioned how the threads resemble those Italian "cakes" around Christmas -- I agree, it strongly resembles panettone crumb. Interestingly, kozunak also appears to be a holiday bread -- Easter, in this case. There are lots of similarities in their creation as well; notably, the substantial amount of eggs and importance of temperature control (keeping the dough warm). Traditional panettone uses only egg yolks, and I've found kozunak recipes that use whole eggs with additional egg yolks.

I am not a professional but my understanding is that the threads come from the eggs(1) and this recipe has lots of eggs.

Beating the eggs will chemically change the protein strands so that they stretch and bind in a similar way to gluten when developed, and similar to a brioche. Brioche dough should be beaten in a stand mixer for a total of 30 minutes to get the smooth texture and long threads(2).

So, next time you make this, try beating the eggs before incorporating and then beating the mixture (holding butter aside) until it slaps the side of the bowl. Then add the butter and beat until it comes together again and slaps the side of the bowl. I think it is the eggs and not so much the gluten what gives your recipe its threads.

(1) see The Science of Cooking

(2) see Baking with Julia