I marinated over night some round steak (cheap cuts, about 1/2 inch thick-ish and on sale for $4 for 4 ... but any red meat would work) in a packet of GrillMates Chipotle Pepper seasoning, mixed with some lime juice and a beer.
I broiled the meat for 3 minutes each side (until it was about medium done, because that's how I like it)
I let the steaks cool, then diced them up into smallish chunks and threw in a bowl. I diced an onion and tossed that in there with some fresh chopped cilantro.
The corn tortillas were made per the masa package instructions It's just masa (corn flour) and water, roll into balls and press in a tortilla press (or between 2 heavy books), and then cook them in a dry pan or griddle for about 45 seconds each side.
I topped each taco with light sour cream.