1. To make culurgiones dough: Pile the flour and semolina on a flat work surface. Make a well in the centre. Pour 3/4 cup salted water into the well. Use a fork to gradually draw in the flour from the inside of the well continuing until the flour and semolina are combined. Knead until the dough is smooth and elastic. Cover with a bowl or tea towel and let rest for 1 hour.
2. To prepare the sauce: Heat oil in a saucepan over medium heat and add 50g onion. Cook until soft, then add the passata and cook for another 20 minutes, adding a sprig of basil leaves at the end.
3. To prepare the filling: First, peel the potatoes and mash in a bowl. Cut a handful of mint leaves into thin slices. Heat 2 Tbsp. oil in a frying pan over medium heat and add 150g onion and the garlic. Cook but do not brown. Next, add the mashed potatoes, 150g grated Pecorino cheese and the sliced mint leaves. Mix well and season with salt.
4. Bring water to boil in a 5l pot and salt.
5. To form the culurgiones: Divide the pasta dough into 5-6 sections. Roll out each section into a ⅛” layer, working a little at a time, then cut out 3” discs. Place a Tbsp. of filling on each disc and seal by bringing the opposing edges together to form the traditional half-moon shape.
6. Add the culurgiones to the boiling water and cook for 4-5 minutes, remove and toss in the tomato sauce, top with a generous amount of grated pecorino, and a few mint leaves to taste.