Blanch spinach leaves in two cups of boiling salted water for five minutes. Drain, refresh in cold water and squeeze out excess water. Finely chop. Mix spinach, peas and potatoes. Add green chillies, ginger, coriander leaves, chaat masala and salt to taste. Add cornflour for binding. Divide the mixture into twenty-four equal portions. Shape each portion into a ball and then press it between your palms to give it a flat tikki shape.