You can use a stand mixer with a paddle attachment or a food processor to prepare it.

In a bowl,  mix the flour and salt, then add the butter, cut into small cubes.

Sand the whole thing with your fingertips to obtain a sandy texture like couscous.

Dilute the egg yolk in the water, then pour this mixture over the sandy dough. Always stir with your fingers to bring the ingredients together and form a dough. Avoid kneading to prevent activating the gluten. This will give you an elastic dough that's difficult to roll out and will collapse during baking.

To do this, push the dough in front of you, press it gently with the heel of your hand, pull it back, and then repeat the motion by pushing it forward again..

Do this 2 or 3 times, then gather the dough into a ball. Flatten the dough ball slightly. Cover in cling film and refrigerate for at least 1-2 hours before use.

Once out of the fridge, the dough will be quite hard. Be careful, as the dough should be firm while remaining pliable, without becoming brittle due to the cold.. let it to come to room temperature before handling.

cover a preferably perforated baking sheet with parchment paper and place the buttered tart ring on top of it.

Roll out the shortcrust pastry on a lightly floured work surface or between two sheets of baking paper. Spread to a thickness of 3 mm (0.11 in )

If the dough becomes sticky, refrigerate for a few minutes to firm up.

Press the pastry well into the bottom of the circle and around the edges. Flatten the dough to a neat edge.

Prick the bottom with a fork to prevent it from puffing up during baking.

put the circle in the freezer for 30 minutes, but this is not essential.

Wash and thinly slice the zucchinis.

Fry for about 5 minutes in a heated frying pan with 2 tablespoons of olive oil. Season with 2 pinches of salt and pepper.

Remove when they begin to turn slightly translucent and start to brown. don't let them take on color.

Remove them to a plate and leave to cool.

Coarsely chop the onion and fry it in 2 tablespoons of olive oil until translucent. Season with salt and pepper.

Pour into a bowl and leave to cool.

Drain the canned tuna and flake. Set it aside

In a bowl, mix the eggs with the cream, salt, pepper and nutmeg to taste. Mix well.

Preheat your oven to 180°C (350°F).

Remove the baking sheet with the tart ring from the freezer.

Coat the bottom of the pan with the mustard and cover with the onion.

Crumble the tuna over the top, then arrange the zucchini slices on top. Start with the edges, overlapping the slices as shown in the picture below"

Pour the egg and cream mixture over the top, but not all the way to the edge, to prevent the cream from overflowing during cooking.

Sprinkle with grated cheese and a little fresh thyme or oregano. You can use dehydrated ones.

Bake the tart in the preheated oven for about 40-55 minutes, or until golden brown and the top is firm to the touch. (cooking time will depend on your oven)

Once baked, remove the tart from the oven and allow to cool slightly before unmolding.

Serve the zucchini and tuna tart warm or at room temperature. Serve with a green salad for a balanced meal.

This savory zucchini and tuna tart is perfect for a friendly lunch or dinner. Its Mediterranean flavours and mix of textures make it a dish that everyone will enjoy. It's the perfect tart to accompany barbecues with friends on a summer's evening.