Marinate the chicken: Combine the vegetable oil, lime juice, salt, chili powder, cumin, smoked paprika and garlic powder in a shallow bowl. Marinate the chicken in this mixture for at least 30 minutes, up to overnight.
Make the corn topping: Whisk the mayonnaise, sour cream, chili powder, salt and lime juice in a medium bowl. Fold in the diced jalapeños, chopped cilantro and cooked corn. Set aside.
Cook the chicken: Preheat oven to 400F degrees. Place the chicken on an ungreased baking sheet or in a glass baking dish. Roast for 20-25 minutes. Slice into strips. Alternatively, air fry at 375F degrees for 6-7 minutes per side or grill over medium heat for 6-7 minutes per side.
Prepare the bowls: Peel and pit the avocado and cut it into slices. Chop the scallions. Crumble the cotija cheese.
Assemble the bowls: Divide the cooked rice into 4 serving bowls. Top with the Mexican street corn mixture, sliced chicken, avocado, scallions, cotija cheese and pickled red onions.