Thickly slice the Toma'muse® tomatoes. Whisk the lemon juice, oil, sugar and salt and pepper together in a bowl. Add the Toma'muse®, capers and gherkins and stir gently to combine. Cover and set aside for 15 minutes.
Score the snapper skin 2-3 times and season with salt and pepper. Heat oil in a large non-stick frying pan over medium-high heat. Cook 2 pieces of snapper, skin side down for 4 minutes, pressing down with a spatula to keep flat. Turn and cook for 1 minute or until just cooked through. Remove to a plate, skin side up. Keep warm while cooking the remaining snapper.
Combine the mayonnaise and harissa and spoon onto 4 serving plates. Top each with a piece of snapper. Add the coriander and mint to the Toma'muse®, stir gently and spoon over the snapper. Serve with crispy potatoes or fries.