Steam vegetables in pressure cooker. Drain well after cooking to remove excess moisture. Heat oil in a frying pan, add ginger garlic paste and then onions. Fry for few minutes and then add minced chillies, turmeric, cooked vegetables and salt. Stir in a high flame till moisture is absorbed completely. Squeeze lemon and add coriander leaves and remove from fire. When cools down make medium sized balls. Mix all the ingredients as mentioned and prepare a thick batter by mixing with water. Dip the balls one by one in the batter and put in hot oil. Deep fry till golden brown.