Season chicken with 1/4 teaspoon kosher salt, garlic powder and black pepper, to taste.
Heat a large nonstick skillet over high heat. When hot add 1/2 teaspoon oil and add half of the chicken.
Cook 2 to 3 minutes on each side, until no longer pink in the center and browned on the edges. Set aside.
Repeat with remaining chicken.
Add the remaining 1/2 teaspoon of oil, onion and garlic and cook over medium heat about 2 minutes, until soft. Add the riced vegetables (frozen), 1/4 teaspoon salt and pepper and cook 5 to 6 minutes, until heated through.
Return the chicken to the skillet, top with the cheese and cover.
Cook low heat until the cheese is melted, about 2 to 3 minutes.