In a bowl, combine lime juice, orange juice, garlic, cumin, oregano, paprika, black pepper, and salt.
Place the flank steak in a resealable plastic bag or shallow dish and pour the marinade over it. Refrigerate for at least 1 hour, preferably overnight.
Remove the steak from the marinade and pat dry with paper towels.
Heat olive oil in a large skillet over medium-high heat. Add the steak and cook for about 4-5 minutes per side, or until the steak is cooked to your desired doneness. Remove the steak from the skillet and let it rest for a few minutes.
In the same skillet, add the sliced onions and bell peppers. Cook until they are softened and slightly caramelized, about 5-7 minutes.
Slice the rested steak into thin strips. Serve it over the cooked onions and bell peppers.
Enjoy your meal!