In a large skillet, brown the ground beef, adding the peppers and onions. When done, drain, and return to skillet. Stir in the corn, tomatoes, sour cream, and chili powder. In another bowl prepare the cornbread mix following directions on the package.
Pour beef mixture into a 9 x 13 inch baking dish. Spoon cornbread batter evenly over the top. Evenly spread the cheddar cheese over the batter and bake following the directions on the cornbread mix until cornbread is done and top is lightly brown.