Mix picante sauce, cumin, oregano, chicken, cheese, and onions. Place about 1/2 cup chicken mixture in center of each tortilla. Fold opposite sides over filling. Roll up from bottom and place seam-side down on baking sheet. Brush with margarine.
Bake at 400 F for 25 minutes or until golden. Garnish with additional cheese and green onion. Serve with additional picante sauce. Makes six chimichangas.