1. Mix all the dipping sauce ingredients together and set aside. Mix the plain flour and cornflour together in a large bowl; season. Add the eggs and 110ml cold water, then whisk to a smooth batter. Divide between 2 jugs.
2. Heat 1 tbsp oil in a 23cm non-stick frying pan over a medium heat. Make the first pancake: reserve 3 tbsp batter from one jug, then pour the rest into the pan, swirling over the base. Scatter over ½ each of the cauliflower, salad onion, chilli and prawns. Drizzle over the reserved 3 tbsp batter and fry for 4 minutes, until the underside is golden and crisp. Using a fish slice or palette knife, flip the pancake and fry for 3-4 minutes, until cooked through.
3. Invert onto a plate, keep warm and repeat with the remaining batter and ingredients. Cut the pancakes into wedges and serve immediately, with the dipping sauce.