Squeeze out all the water from the grated onions.
Place onions in a large bowl.
Add onions, garlic, ginger, green chili, coriander (cilantro) leaves, mint leaves, ground coriander, ground cumin, garam masala, red chili powder, ground black pepper and amchur.
Season with salt.
Mix well.
Cover and refrigerate for 1 hour.
Divide the mixture into 8-10 portions.
Press each portion firmly onto oiled wooden skewers, each one around 12-14 cm long.
Place a skillet or frying pan over medium-high heat.
Add oil.
Cook kebabs for about 10 minutes, turning 4-5 times, or until well browned on the outside and cooked on the inside.
Cook in batches if needed. Do not overcrowd the pan.
Serve with naan, cucumber salad and raita.