For the dressing, mix the lemon juice with the sugar and season with salt and pepper. Peel the garlic and crush into the mixture and then stir in the oil.
For the salad, peel the onion and cut into fine columns. Chop the cucumber into cubes. Trim and chop the bell peppers. Drain the capers and olives. Cut the cheese into cubes.
Mix the prepared salad ingredients together and transfer to plates. Drizzle with the dressing and serve seasoned with colored pepper.