Step 1

Line a plate with paper towels or a kitchen towel and arrange the tomatoes on top. Season them all over with salt and set aside to drain.

Step 2

Meanwhile, zest and juice the lemons. You should have 2 tablespoons of zest and at least 1/4 cup of juice. Transfer the zest and 3 tablespoons of the juice to a blender or food processor, then grate the garlic into the blender.

Step 3

Drain the tuna and anchovies, but don't toss the oil. Add the tuna, anchovies, mayonnaise, mustard, capers and a few good grinds of pepper to the blender. Blend the mixture on medium speed until very smooth, about a minute or less. With the blender running, slowly drizzle in 2 tablespoons of the reserved tuna or anchovy oil. Taste the tonnato and season with more lemon juice and salt as needed.

Step 4

Arrange the tomatoes on a serving platter and pour over as much tonnato as you'd like (I like a lot). Drizzle with olive oil, and sprinkle with a bit of flaky salt, more pepper and chile flakes (if using). Serve immediately.