Kabobs to Fajitas - how to make the meat tender

1. Slice it thinly across the grain.

That's it.

If it's properly sliced, it'll be tender, as there isn't enough internal structure left for it to resist it falling apart.

Even though it's not technically the correct way to to cook fajitas, I'd go with a mix of Bruce's #1 and 2 : simmer it 'til warmed through in an appropriately flavored liquid (a mix of lime juice and any generic italian salad dressing works well), then drain, and give it some some fast heat to sear.

Of course, this assumes that they're already cooked ... if they're not, then just marinate, cook, and slice (again, against the grain).

A few options:

1. Low and slow. Reheat the meat slowly in the oven (or slow cooker) at a low temperature (above 165F) in a tasty liquid.

2. Faster + hackier. Store overnight in something like the braising liquid from #1, with some acidic base (lime, for example). Reheat normally.

3. Smash to bits. Before reheating, put the meat in a baggie and smash with the butt of your knife (or some other smashing tool). You could also use a rolling pin.

You can take any meat and slice it thinly to make it instantly tender, adding an au jus or sauce and voila!