What is the technique for Vacuum Flask Cooking?

It's a slow-cooking technique involving a thermal cooker, or vacuum flask, The pot/flask and contents are heated to cooking temperature, and then sealed in the flask. The flask more or less eliminates heat loss, so the food remains at cooking temperature for a long time, and slow-cooks without continued heating.

See this Wikipedia article for more info:
http://en.wikipedia.org/wiki/Vacuum_flask_cooking

I've had excellent results using my vacuum flask cooker to do slow-cooked eggs. Also known as 63° eggs because they're usually sous vide cooked to 63° C. These eggs are a feature at fancy restaurants all over New York. Here's a picture of a dish from Eleven Madison Park:

from my favorite English-language Japanese cooking blog, justhungry.com

Provided you have the equipment (vacuum cooker, thermometer) and your tap water is hot enough, these eggs could not be easier. You do them without even turning on the stove.

1. Put four or more eggs in a bowl.
2. Run your tap water on hot until it won't get any hotter. Take a temperature reading and make sure your hot water is hotter than 64° C (147° F). Don't worry if it's much hotter than this. That's actually good.
3. Cover the eggs with hot tap water. Fill the vacuum flask cooker a quarter of the way with hot tap water and close. Go do something else for 10 minutes. (Boil the pasta?)
4. Run the tap again to get hot, dump the water from both bowl and cooker.
5. Fill cooker 2/3 way with hot tap water. Put eggs in the cooker. (I use a steamer basket to keep them suspended in the middle of the water, but I'm not sure it's totally necessary.)
6. Take a temperature reading and adjust the water to 64° C (147° F) by adding cool water, if necessary.
7. After 30 minutes, take the eggs out with a slotted spoon and crack them over whatever you want to make more delicious.

Agreed with gkrogers.

The good way of using Vacuum pot/flask include the following:

1. Make any type of Stock
2. Cook Stew
3. Make Curries

If you want to use it as a real Chinese, you must try this dish

Cantonese Braised Beef Brisket with Daikon (White) Radish

Ingredients:

• 650g Beef Brisket chopped into chunks
• 450g Daikon Radish - peeled and chopped into chunks 1/4 cup
• Shaoxing Wine [ or any rice wine]
• 5 slices Ginger
• 3 cloves Garlic - crushed 1
• 1/2 tbs Chu Hou Sauce
• 1 Star Anise
• 1 Cinnamon Stick
• 1 small piece of Rock Sugar [ Or Brown Sugar]
• Light Soy Sauce Cornstarch Slurry

Directions:

• Brown beef in a large pot with a little bit of oil then remove from pot.
• In the same pot, add ginger and garlic, saute until fragrant.
• Deglaze with Shaoxing wine.
• Add beef brisket.
• Mix in Chu Hou sauce.
• Add star anise, cinnamon stick, rock sugar and enough water to cover all ingredients.
• Add radish, bring liquid to boil, lower heat and cover to simmer until meat is tender (at least 1 1/2 hours).
• Stir the ingredients around half way through.
• Add light soy sauce to taste.
• Thicken with corn starch slurry.

http://www.pigpigscorner.com/2009/05/cantonese-braised-beef-brisket-with.html