Mix the flour with 180ml water until fully combined. If you have time, leave to stand for 30 mins. Meanwhile, toss the onion with the lemon juice in a separate bowl.
Heat 1 tsp of the oil in a large non-stick frying pan over a low heat and pour in half the batter. Swirl the pan to coat the base evenly and cook for about 6 mins until firm and you can lift the edge of the pancake off the pan. Using a spatula or palette knife, turn the pancake over and cook for 4-6 mins on the other side, until cooked through and crisp at the edge. Keep warm in a low oven while you cook the second pancake in the same way.
Spread hummus down the middle of each pancake, then top with the tomatoes, quick-pickled onions, coriander and salad leaves. Fold in half to serve.
