To make the pancake batter; in a bowl add refined flour, gram flour, turmeric powder, crushed black pepper, salt, milk and baking soda and whisk.
In a hot pan add oil. Make a patty of the filling and pan sear it from both sides.
In another pan add the batter and make a pancake. Once cooked, remove and cut with a ring mould. Make one more.
Place one pancake on a plate. Add sliced onion, prepared patty, sliced tomato, sliced cucumber and gherkins and cover with the other pancake to make a burger.
Serve the lentil pancake burger with tomato ketchup.