Heat oven to 350°F. Spray 9-inch square or 12x8-inch pan with nonstick cooking spray. Cut peppers in half lengthwise: remove stems, seeds and membranes. Place pepper halves in boiling water for 5 minutes or until slightly softened; drain, Set aside.
In large bowl, combine kidney beans, % cup of the tomato sauce, corn, rice, green onions, teaspoon oregano and garlic powder; mix well. Fill each pepper half with 1/6 of bean mixture; place in spray-coated pan.
Bake at 350°F. for 30 minutes. Sprinkle cheese over each pepper half; bake an additional 3 to 5 minutes or until cheese is melted.
In small saucepan, heat remaining tomato sauce and 1/4 teaspoon oregano. Serve warm sauce over hot stuffed peppers.