In a bowl, combine olive oil, lime juice, chili powder, cumin, garlic powder, salt, and black pepper. Add the sliced chicken and steak, and marinate for at least 15 minutes.

Preheat the grill or skillet over medium-high heat. Cook the marinated meat for about 5-7 minutes on each side until fully cooked.

In the same skillet, add the sliced bell pepper and onion. Sauté for about 5 minutes until they are tender.

Warm the tortillas on the grill or in a skillet. Serve the grilled meat and sautéed vegetables in the tortillas, topped with sour cream, cheese, guacamole, and salsa.