If using fresh tomatoes: bring a pot of water to a boil. Score a small X on the bottom of each tomato, plunge into boiling water for 20–30 seconds, then transfer to an ice bath. Peel off skins, core and finely chop until you have about 1 cup. If using canned high-quality chopped tomatoes, drain excess liquid and roughly chop if needed.

Drain and flake tuna

Open the tuna can and gently drain most of the oil (reserve 1–2 tablespoons for flavor if you like). Transfer tuna to a bowl and use a fork to flake into large, tender flakes; avoid overworking to preserve texture.

Combine aromatics

In a medium bowl, combine the chopped tomatoes, minced onion, garlic (if using), and chopped parsley. Stir gently to distribute evenly.

Dress the mixture

Add the extra-virgin olive oil, sherry vinegar, and lemon juice to the tomato mixture. Season with sea salt and freshly ground black pepper. Taste and adjust acidity, salt, or oil as needed—add more vinegar or lemon for brightness, or a teaspoon more oil for silkiness.

Fold in tuna

Gently fold the flaked tuna into the dressed tomato mixture, keeping large flakes intact. Let the mixture rest for 10–15 minutes at room temperature to allow flavors to meld.

Final seasoning

Before serving, taste and adjust seasoning. If the mixture seems dry, drizzle 1 additional tablespoon of olive oil. Sprinkle a little extra chopped parsley for freshness.

To serve

Toast or slice the crusty bread and warm briefly if desired. Spoon generous portions of the Ortiz tuna mixture onto bread slices, or serve alongside mixed salad greens dressed simply with olive oil and vinegar.

Serve immediately as an open-faced tapa, light lunch, or starter. Leftovers can be refrigerated in an airtight container for up to 2 days; bring to room temperature before serving for best flavor.