In a bowl add mashed potato, green chili, ginger, garlic, lemon juice, cumin seeds, turmeric powder, coriander leaf 1/2 teaspoon (tsp.) oil, salt from the section "== For Making Vada ----" and mix them to a douch and keep it aside for some time.
In the bowl add the ingredients from the section "== For Making Batter ---s" and add water as needed and make a batter like you do fro bhaji .
In a pan heat oil to deep fry. Make small balls out of the potato dough. Now dip the potato ball in the gram fllur batter and deep fry them to golden brown in bathes.
Take each bun coat the inside with mint chutney. Now place the fried balls in between the bun slices and serve.