Pat the red snapper fillet thoroughly dry with paper towels. Using a very sharp knife, slice the fillet into 1/4-inch (6 mm) thin slices or small bite-sized slices appropriate for crudo. Arrange the slices in a single layer on a chilled plate or shallow dish.

Make the citrus marinade and season

In a small bowl whisk together the lemon juice, lime juice, 2 tablespoons extra-virgin olive oil, 1 tsp fine sea salt and 1/2 tsp freshly ground black pepper. Taste and adjust acidity or salt slightly; the mixture should be bright and balanced.

Marinate the fish

Spoon the citrus mixture evenly over the arranged snapper slices so each piece is lightly coated. Cover loosely and refrigerate for 8–12 minutes — the acid will slightly cure the surface without fully cooking the fish (for a true crudo texture keep it on the shorter end).

Tomato & Olive Relish

Combine relish ingredients

While the fish marinates, place the halved cherry tomatoes, chopped kalamata olives, finely minced shallot, sliced mint, finely diced red chili, chopped capers, 1 tsp white wine vinegar and 1 tsp olive oil into a medium bowl.

Season and macerate

Add 1/2 tsp coarse sea salt and 1/4 tsp freshly ground black pepper. Stir gently to combine. Let the relish sit at room temperature for 8–10 minutes to allow flavors to marry; if the tomatoes are very firm you can let it sit up to 20 minutes.

Plating & Finishing

Assemble the crudo

Remove the marinated snapper from the refrigerator. Using tongs or a spatula, transfer slices to chilled serving plates in a single decorative layer (overlapping slightly is fine). Spoon the tomato-olive relish evenly over the fish slices, distributing shallot, chili and olive pieces so each bite has a bit of everything.

Finish and garnish

Drizzle about 1 tablespoon of good-quality extra-virgin olive oil over the assembled crudo. Scatter microgreens or small mint sprigs and place thin citrus rounds on the side or atop the fish as desired. Finish with a light sprinkle of flaky sea salt.

Serve

Serve immediately while the fish is cool and the relish is fresh. Provide small forks or spoons so guests can scoop both fish and relish together. Best eaten within 20 minutes of plating for optimal texture.