Drain the water out and cook the dal with 1/2 cup of water on low heat for 5 minutes.
After the dal gets soft, add garam masala and chat masala powders and coriander leaves. Stir and mix well. Set aside from heat.
Mix corn flour and green chillies with mashed potatoes. Set aside.
Heat a deep frying pan with soybean oil.
Meanwhile grease the palm of your hand with some soybean oil and take a ball of mashed potatoes to make flat round shape. Fill the center with the cooked dal mixture. Cover with more mashed potatoes and then press gently to make a flattened aloo tikki.
Deep fry 3-4 aloo tikkis in batches until golden brown. Serve with ketchup.