Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the sliced flank steak and cook for 3 to 4 minutes until browned but still slightly pink inside. Remove the steak to a plate and set it aside.
Add the remaining tablespoon of olive oil to the same skillet. Place the sliced bell peppers and onion in the pan. Cook for 5 to 6 minutes, stirring occasionally, until the vegetables soften and start to char at the edges.
Return the steak to the skillet. Sprinkle in the cumin, chili powder, garlic powder, salt, and black pepper. Stir everything together and cook for 2 more minutes so the spices coat the meat and vegetables evenly.
Remove the skillet from the heat and drizzle the lime juice over the mixture. Stir once to combine.
Warm the whole-wheat tortillas in a dry skillet or microwave for 20 seconds. Spoon the steak and vegetable mixture into each tortilla and top with chopped fresh cilantro before serving.