In a small bowl combine mayonnaise, chopped cornichons (or pickles), chopped capers, finely chopped shallot, lemon juice, Dijon mustard and chopped parsley. Season with salt and pepper to taste. Stir until smooth, cover and refrigerate for at least 15 minutes to let flavors meld.

Salad garnish

Prepare salad

In a medium bowl combine mixed salad leaves, sliced cucumber, sliced red onion and halved cherry tomatoes. Drizzle with 1 tablespoon olive oil and 1/2 teaspoon lemon juice. Season with 1/4 teaspoon salt and 1/4 teaspoon black pepper. Toss gently and set aside chilled while you cook the fish.

Whitebait

Prepare dredging mixture and batter

Pat the whitebait dry with paper towels and place in a bowl. In a shallow dish whisk together flour, cornmeal (if using), 1/2 teaspoon black pepper, 1 teaspoon salt and garlic powder (if using). In a second bowl beat the eggs and then whisk in the cold sparkling water to make a light batter. Keep both dry and wet mixtures ready.

Heat oil

Pour enough vegetable oil into a wide skillet or shallow frying pan to give about 1/2 inch (1–1.5 cm) depth. Heat over medium-high until oil reaches 175°C (350°F) or is shimmering. If you don't have a thermometer, test with a pinch of flour — it should sizzle immediately.

Coat and fry

Working in batches to avoid overcrowding, dredge small handfuls of whitebait first briefly in the flour mixture, then dip into the egg-sparkling-water batter allowing excess to drip off. Carefully add to hot oil in a single layer. Fry 1.5–3 minutes per side, or until the coating is crisp and pale golden and the fish are cooked through. Use a slotted spoon or spatula to turn if needed.

Drain and season

Remove fried whitebait to a wire rack set over a baking sheet or onto paper towels to drain. Immediately sprinkle with a light pinch of salt and a little cracked black pepper. Keep in a warm oven (90–100°C) if frying remaining batches so all are served hot.

Serve

Arrange warm whitebait on a serving platter with lemon wedges, the chilled tartar sauce in a small bowl and the salad garnish alongside. Encourage diners to squeeze lemon and dip whitebait into tartar sauce. Serve immediately.