In a small bowl mix the soup and sour cream; set aside.
Melt margarine in a medium saucepan over medium high heat. Add onion and chili powder, and saute until tender. Stir in the chicken, chile peppers, and 2 tablespoons of the soup mixture. Cook and stir until heated through.
Spread 1/2 cup of the soup mixture in a 9x13 inch baking dish. Spoon about 1/4 cup of the chicken mixture down the center of each tortilla. Roll up tortillas, and place, seam-side-down, in the baking dish. Spoon remaining soup mixture on top, and sprinkle with cheese.
Bake 25 minutes in the preheated oven, or until bubbly and lightly browned.
