1 pound lean, boneless beef chuck, flank, or brisket, cut into cubes (I bought "lean beef stew meat" and it was excellent)
1 medium onion
3 cloves garlic, peeled
2 T oil
15-ounce can diced tomatoes, drained
2 green onion, root ends removed, coarsely chopped
1 jalapeno, seeded and minced (more to taste)
Warmed tortillas, to serve
Taco fixings, to serve (we used sour cream and salsa)
1. Bring 2 quarts of water to a boil in a large saucepan. Add the meat and 1 tsp salt, and skim off the grayish foam that rises to the top. Slice half the onion and halve one clove of garlic and add to the meat. Reduce heat, and simmer until the meat is very tender, about 1 hour (or up to 90 minutes depending on the cut). Let cool, and chill in the fridge overnight.
2. The next day, spoon off the fat that has risen to the top. Transfer the meat to a cutting board, and strain the broth.
3. Shred or chop the beef into small pieces.
4. Mince the remaining half onion and 2 garlic cloves. Heat the oil in a large skillet over medium-high heat, and add the onion and garlic. Saute for about 5 minutes, and then add the beef. Cook until well browned and starting to get a bit crispy in places, about 8-10 minutes. Watch things carefully and make sure to stir every so often. (You don't want to stir constantly or a crust will not be able to form on the meat.)
5. Turn the heat down to medium, and add the tomatoes, green onions, and jalapenos. Cook for about 4 minutes. Stir in 2/3 cup of the reserved broth, and simmer until the liquid has evaporated but the meat still looks nice and juicy (about 8-10 minutes). Season with salt to taste, and serve wrapped in warmed tortillas.