Put the flour in a bowl and pile it up creating a “well” in the centre. Pour the sourdough starter and the water into this “well”, a little at a time, and stir with a fork. Add 4 spoonfuls of olive oil and mix again, then continue with your hands until the mixture is homogenous. Transfer it onto your work surface, dusted with a little flour, and knead vigorously until you have a compact, smooth ball of dough. Put it in a bowl covered with cling film and leave it in the fridge overnight to rise. The following morning, take the bowl out of the fridge and leave to rise for another 3 hours at room temperature (if you want to reduce the rising time, use 12 g of fresh yeast instead of the sourdough starter and leave the dough to rise for 2 hours at room temperature, preferably at 18-20 °C). In the meanwhile prepare the filling: mix the ricotta (previously mashed with a fork) in a bowl with the grated pecorino, the sausages (skinned and crumbled with your fingers), the Carciofini Trifolati well drained of their liquid, the marjoram, grated lemon peel, salt and pepper. When the dough has risen, roll it out with a rolling pin (using a little flour so that it doesn’t stick) to form a disk with a diameter a bit larger than the tin in which you will cook the tart. Place the disk of dough in the tin, which you have greased with a spoonful of oil and dusted with flour, making sure it also adheres around the side. Pour in the filling, spread it out and level the surface. Fold the edge of the dough inwards and brush the entire surface with the beaten egg yolk. Cook the tart in a preheated oven, at 180 °C, for 35-40 minutes, until it turns a nice golden colour. Before serving, leave it to rest for about 10 minutes. This tart can be eaten as an appetizer, but also as a main course accompanied by salad leaves or other raw vegetables. It’s delicious straight away, still lukewarm, but it also keeps well and is also excellent cold.