In a bowl, mix 200 grams of boiled and mashed rajma (kidney beans) with 1 finely chopped onion, 1 finely chopped tomato, 1 finely chopped green chili, 1/2 teaspoon red chili powder, 1/2 teaspoon cumin powder, salt to taste, and 1 tablespoon chopped coriander leaves. Set aside.
In another bowl, mix 100 grams of hung curd with 1/2 teaspoon of garlic paste, 1/2 teaspoon of oregano, and salt to taste. Set aside.
Take 4 whole wheat bread slices and spread the hung curd mixture evenly on one side of each slice.
Place a generous amount of the rajma mixture on top of the hung curd layer on two of the bread slices.
Add a layer of thinly sliced cucumber, tomato, and onion on top of the rajma mixture.
Top with the remaining bread slices, hung curd side down, to form the sandwiches.
Heat a non-stick pan or sandwich maker and cook the sandwiches on medium heat until they are golden brown and crispy on both sides.