Begin by marinating the chicken. In a bowl, combine the olive oil, chili powder, cumin, salt, and pepper. Add the chicken breasts and coat well. Let it marinate for at least 15 minutes.

While the chicken is marinating, cook the rice. In a medium saucepan, bring the chicken broth to a boil. Add the rice, reduce heat to low, cover, and simmer for 15-20 minutes until the rice is cooked and fluffy. Set aside.

Grill the marinated chicken on a preheated grill or grilling pan over medium-high heat for about 6-7 minutes on each side until fully cooked (internal temperature should reach 165°F). Remove from heat and let it rest for a few minutes before slicing.

In the last few minutes of grilling the chicken, add the corn to the grill and cook until slightly charred, about 3-5 minutes. Remove from heat.

In a large mixing bowl, combine the cooked rice, grilled corn, diced tomatoes, cilantro, and lime juice. Mix well to combine.

To serve, create a bed of the corn and rice mixture in a bowl, add sliced grilled chicken on top, and garnish with avocado slices and cotija cheese. Drizzle with lime juice and top with mayo and sour cream if desired.

For added flavor, you can mix some taco seasoning into the chicken marinade.