Rinse the rice under cold water until clear. Combine with water and a pinch of salt in a pot. Bring to boil, reduce heat, cover, and simmer for 15 minutes. Let sit covered for an additional 10 minutes before fluffing.
Season chicken pieces with chili powder, salt, and pepper. Cook in a hot skillet for 3-4 minutes per side until golden brown and cooked through (internal temperature should be 165°F). Keep warm.
In a hot skillet, char the thawed corn without stirring for about 3-5 minutes until blistered. Mix mayonnaise, sour cream, lime juice, chili powder, salt, and pepper in a bowl. Add charred corn along with cheese and cilantro.
Assemble bowls with rice as the base topped with chicken and the corn mixture. Garnish with diced avocado and extra cilantro.