Take chopped onion, capsicum, red bell pepper in a bowl.
Add mayonnaise, pepper powder and mix well.
Take one slice of bread and spread a thick layer of mayonnaise and vegetable mixture on the bread slice.
Heat tawa and spread butter on it.
Now place the sandwich on tawa and roast it from both sides until sandwich turns brown and crispy.
Serve vegetable mayonnaise sandwich with tomato ketchup and green chutney.
