Mix onion, peppers, garlic, tomato and vinegar. Season with salt and pepper. Let marinate for a few minutes. In a small frying pan, melt 1/4 cup Gold n Soft margarine and saute the vegatbles while mixing, until shiny. (3 to 4 minutes). Add the rest of the Gold n Soft margarine while adding the cilantro. Serve on top the tostadas. Add cotija or crumbled white cheese before serving.
Tips: Use with soft tortillas to make vegetable tacos. Use recipe with your favorite vegetables. Use this chile and onion mixture over meat, chicken or fish.