Heat oil in a pan.Saute onion till they become soft(no change in colour).Add chopped mushroom and cooked beans.Saute in high flame for few seconds.

Then add paprika and pepper powder.Sprinkle enough salt.Continue to saute in high flame till the mushroom also gets cooked well(this will take only2-3 mints).

Now switch off the flame.Let the mixture cool down.

When the mixture is cool enough add bread crumbs to it and mix well( the bread crumbs act as holding agent:otherwise it will be

Difficult to hold and make patties out of the mushroom and black beans mixture).

Take medium sized balls out of the mixture.Press in your palms and make thin patties.

Now heat little oil in a flat pan.Fry the patties on both sides.Remove from fire.

Arrange the burgers

Cut each burger bun horizontally into two.Apply butter on both sides of each bun.Toast them lightly on the tawa(only the side with butter)

Place the lower half of the bun on a clean, dry surface and spread 1 tbsp of tomato ketchup evenly over it.

Place a lettuce leaf, 1 or 2(depends on the size) tomato slices and 1 onion slice and 1 patty one by one.

Now spread 1 tspn tomato ketchup over the other half of the bun and cover the prepared burger.

Notes: You can use mayonisse /ranch as a spread in the burgers though they are healthier without these spreads.Also you can use 1 slice of cheese in each burger.