Slice chicken breast, bell pepper, and onion into thin uniform strips.
Marinate chicken strips with garlic paste, cumin powder, paprika, salt, and 0.5 tbsp olive oil for 20 minutes.
Heat remaining olive oil in a heavy skillet over high heat.
Stir-fry chicken strips for 6 minutes until charred, then add bell peppers and onions; sauté until tender-crisp.
Warm tortillas on a griddle and serve the sizzling chicken mixture inside.