Wash the tomatoes, halve them and remove the seeds, then throw the tomatoes in a large pot.

Bring the tomatoes to the boil and after 30 minutes scoop all the tomatoes into a large cotton cloth or pillowcase.

Hang the bag so that it can drain all the water, squeezing it often with your hands.

After about 2 to 3 hours, when the tomatoes have lost all the water, pass them through a vegetable mill using the finest sieve.

Collect the tomato purée in a pot, add the salt and cook on low flame, covered, for about 30 minutes, to thicken the sauce.

Brush with olive oil a 37x27 baking sheet. Using a spatula, spread the thick tomato purée in an even layer to cover the entire baking sheet.

Preheat the oven to 100°C (212°F). Use the convection fan if you have one.

Place the baking sheet in the oven and bake for about 7 hours, or more. It will depend on the thickness of your tomato purée. Every 30 minutes stir the purée with the spatula to dry it evenly and prevent it from forming a crust.

Let the tomato paste cool to room temperature, then spoon it into clean jars. Level the surface with the back of the spoon.

Put the jars in a large pot and cover with water: bring to a boil. Simmer for 20 minutes and then remove from the heat. Let the jars cool completely in the pot, then remove them from water. You can store them for even an year in a dry, cool and dark place.

When you open the jar of tomato paste, use a spoonful of paste then cover it with olive oil. Keep it in the fridge once opened.