Make the filling: finely chop one small Onion and a handful of Flat-Leaf Parsley; roughly chop a tablespoon of Capers. Drain and flake a tin of Canned Tuna in Oil into a bowl.
Warm a teaspoon of Neutral Oil in a small pan and gently sauté the chopped Onion just until softened and translucent; let cool slightly and add to the bowl with the flaked Canned Tuna in Oil.
Stir in the chopped Flat-Leaf Parsley, chopped Capers, a dab or two of Harissa Paste to taste, a squeeze of Lemon juice, and season with Salt and Black Pepper. Taste and adjust the harissa, lemon, salt or pepper as desired.
Lay a Brik Pastry Sheet flat on your work surface. Spoon the tuna mixture into the center, forming a small well in the middle of the filling for the egg.
Carefully crack one Eggs into the well on top of the filling. Brush the pastry edges with a little water to help seal.
Fold the sheet over into a triangle (or fold the sides to make a neat parcel) and press the edges gently to seal, taking care not to tear the delicate pastry.
Heat enough Neutral Oil in a skillet to cover the base thinly and bring to medium-high heat — it should shimmer but not smoke. Slide the brik in seam-side down and fry for 1–3 minutes per side until the pastry is golden, crisp and the egg is cooked to your liking (shorter for a runny yolk).
Transfer the brik to paper towels to drain briefly, squeeze over a little more Lemon, and serve immediately while the pastry is still crackling. Enjoy hot — the contrast of crunchy pastry and the soft yolk is the point of the dish.
