Sieve the flour into a large bowl. In a jug, whisk the eggs with the water, then whisk them into the flour until smooth. Set aside.
Heat ½ tablespoon of the vegetable oil in a non-stick 20cm frying pan. Add the sliced spring onions, pepper and chilli and fry for 3 minutes, or until softened. Remove from the pan and transfer to a bowl.
Add a little more oil to the pan, then tip in a quarter of the vegetables and a quarter of the prawns. Spread evenly over the base, then pour over a quarter of the batter, tilting the pan to spread evenly. Cook over a medium-high heat for 3 minutes.
Hold a plate over the pancake, then flip the pan, tipping the pancake onto the plate. Slip it back into the pan on the other side and cook for 1 minute until cooked through. Repeat with the rest of the ingredients to make 4 pancakes.
Cut the pancakes into wedges and serve with the dipping sauce.
Mix together the rice vinegar, light soy sauce, chillies, spring onions, garlic and sesame oil. Set aside.