Slice the beef into long strips (fresh is best, but if frozen, thaw first).

Season the beef and cook it in a skillet with a little vegetable oil over medium heat.

Separately, wash the tomatoes, bell peppers, and onions thoroughly. Slice everything into thin strips (julienne) and set aside. Once the beef has released its juices and starts to brown, add a little more water so it simmers again—this will make the meat more tender. Next, add the vegetables and sauté to your liking until they're al dente, or cook a bit longer if you prefer them softer. Add a little salt if desired, and a pinch of paprika (optional).

This main dish goes great with any rice, refried beans, or a delicious Mexican-style cactus salad!