Heat 2 teaspoons of the olive oil in a large pan over medium high heat.
Sprinkle the garlic powder and cumin over the chicken breasts and season the chicken with salt and pepper to taste.
Place the chicken in the pan and cook for 4-5 minutes on each side or until done. Place the chicken on a plate and cover with foil.
Place the remaining teaspoon of olive oil in the pan. Add the red onion and cook for 3-4 minutes or until onion has softened. Add the corn and black beans to the pan and cook for 4 minutes.
Stir in the tomatoes, cilantro and lime juice. Season the mixture to taste with salt and pepper.
Remove the chicken from the plate and add to the pan; heat for 2-3 minutes or until chicken is warmed through. Serve, garnished with additional chopped cilantro if desired.