Prepare the bean patty: In a bowl, mash 200 grams of boiled rajma (kidney beans) and mix with 1 finely chopped onion, 1 finely chopped green chili, 1/2 teaspoon red chili powder, 1/2 teaspoon cumin powder, 1/2 teaspoon garam masala, salt to taste, and 2 tablespoons of breadcrumbs. Mix well and form 4 equal-sized patties.

Heat 2 tablespoons of oil in a non-stick pan over medium heat. Cook the patties for 3-4 minutes on each side until they are golden brown and crispy. Set aside.

Prepare the spicy mayo sauce: In a small bowl, mix 4 tablespoons of mayonnaise with 1 tablespoon of tomato ketchup, 1/2 teaspoon red chili powder, and a pinch of salt. Set aside.

Assemble the burgers: Slice 4 burger buns in half and toast them lightly on a pan. Spread a layer of spicy mayo sauce on the bottom half of each bun. Place a lettuce leaf, followed by a bean patty, a slice of tomato, a slice of onion, and a slice of cheese. Spread another layer of spicy mayo sauce on the top half of the bun and place it on top of the cheese.

Serve the Mexican burgers immediately with a side of potato chips or fries.