To a bowl add the yogurt, cucumber, mint, cumin and salt, mix well. Set aside.
To a food processor, add the chickpeas, potato, onion, tomato, ginger, salt and spices. Pulse until the ingredients are blended, still chunky, not over blended. Just until there are no large chunks of onion. You may need to scrape down the sides of the bowl to help mix properly. The dough should stay together when squeezed in your hand. If not, or too sticky add a little of the flour until no longer sticky. Refrigerate the mix for 30 minutes, uncovered. This will help eliminate an excess moisture and help them stay together.
After refrigeration, form the mix into 4 tightly packed balls, then shape into patties.
Add oil to a heavy or cast iron skillet and heat over medium heat. When hot, carefully add the burgers. Cook for 4-5 minutes, until a crust develops.. Do not move or turn, the crust will help the burger stay together. Turn carefully and cook on the other side until a crust develops.
Serve between slices of naan bread with lettuce leave, raita and red onion.