In a medium bowl, mix the flaked tuna, chopped parsley, capers, diced onion, and lemon zest. Season lightly with salt and pepper.

Heat about 1 inch of vegetable oil in a large, deep frying pan over medium-high heat until hot.

Lay out a pastry sheet on a flat plate. Place a quarter of the tuna mixture in the center and flatten it slightly to create a small well or nest.

Crack one egg carefully into the center of the tuna nest.

Fold the pastry sheet over the filling to form a triangle or half-moon shape, pressing the edges briefly to seal.

Immediately slide the brik into the hot oil. Fry for about 1-2 minutes on each side until golden brown and crispy, ensuring the egg white is set but the yolk remains runny.

Remove from the oil and drain on paper towels. Repeat the process for the remaining briks.

Serve immediately while hot with extra lemon wedges on the side.