Heat sufficient oil in a kadai.
Whisk together gram flour, ½ tsp red chilli powder, carom seeds, soda bicarbonate, salt and sufficient water to make a thick and smooth batter. Rest the batter for some time.
Deep-fry the cauliflower florets in hot oil till half done. Drain on tissue papers. Squeeze between tissue papers to remove excess oil and place them in a bowl.
Sprinkle the remaining red chilli powder, dried mango powder, black salt, chaat masala. Add green chutney, salt, lemon juice and mix well.
Dip the cauliflower florets in the batter and deep-fry till golden and crisp. Drain on absorbent paper.
Transfer onto a serving plate. Sprinkle chaat masala and serve hot.