Cook ground beef, onion, and green pepper in a skillet until beef is browned, stirring to crumble.
Drain; stir in 1 cup shredded cheese and next 5 ingredients, mixing well.
Wrap tortillas tightly in aluminum foil; bake at 350° for 15 minutes.
Place a heaping 1/3 cup of meat mixture on center of each tortilla.
Fold bottom edge of tortilla up and over filling just until mixture is covered.
Fold in one side of tortilla to center; roll up.
Repeat with remaining tortillas.
Place burritos in a greased 13- x 9- x 2-inch baking dish; set aside.
Combine tomato sauce, chili powder, and 1 tea spoon cumin.
Bring mixture to a boil; reduce heat and simmer 5 minutes.
Spoon sauce mixture over burritos.
Cover and bake at 375° for 15 minutes.
Sprinkle remaining 1 cup cheese over top, and bake an additional 5 minutes.
Serve with sour cream, if desired.