You Will Need
Mix the flour and salt. Mix the oil with the water. Add the liquid to the flour and mix, first stirring with a wooden spoon, and then kneading well by hand. Put the dough into a bowl, cover and rest in the refrigerator for 20 minutes.
Divide the dough into four uniform pieces and roll them out over a well-floured work surface.
Mix the passata and tomato purée together. Finely chop or crush the garlic and add it to the tomato mixture together with the sugar, oregano, salt and pepper.
Remove the stalks from the cavolo nero and cut the leaves into thin strips. Add them to the sauce.
Slice the mozzarella.
Heat 4 small cast-iron frying pans (16–18 cm) over indirect heat with the lid of the barbecue closed.
Put ½ tablespoon olive oil in each pan. Line the pans with the dough, spread with the filling, and top with mozzarella. Drizzle the rest of the oil over the pies and bake over indirect heat with the lid closed for 15 minutes.