In a medium bowl, mix the mayonnaise, sour cream, lime juice, and half of the cilantro. Set aside.
Season the chicken breasts with chili powder, cumin, garlic powder, salt, and pepper.
Heat the olive oil in a large skillet over medium-high heat. Add the chicken and cook for 6-7 minutes on each side, or until fully cooked and no longer pink in the center. Remove from the skillet and let rest for a few minutes before slicing.
In the same skillet, add the corn and cook for 3-4 minutes until heated through and slightly charred.
To assemble the bowls, start with a base of cooked rice. Top with sliced chicken, charred corn, diced red onion, avocado slices, and a generous drizzle of the mayo-sour cream mixture.
Sprinkle with crumbled feta cheese and the remaining cilantro before serving.