Julienne the onions and the red pepper.

Heat 4 or 5 tbsps of extra virgin olive oil and fry lightly the onion and pepper.

Strain the sauce and reserve the oil (we will use it to make the dough).

Mix the tuna with the onion and peppers and let settle while preparing the dough.

Put in the Thermomix glass 100 g of oil from having made the filling, 130 g of water, 50 g of milk and 20 g of baker's yeast.

Program 90 seconds, 40º C, speed 3.

Then add 400 g of strength flour and a teaspoon of salt.

Knead 2 minutes / bread mode.

Remove the dough from the glass and work by hand until integrating 100 g more of flour.

Let settle, covered, for 1 hour.

Preheat the oven to 200ºC

Cut the dough into 2 halves. Shape each one of them into rectangles the size of the oven dish.

Place one of the halves onto the dish and spread the filling over it.

Cover with the other half. Seal the edges and make a hole in the center.

Paint with beaten egg and bake for 30 minutes (200ºC)

Let cool on a wire cooling rack.