Combine the flour with water, little by little until it just comes together to form a dough (between ½-1 cup). Knead the dough for 5 minutes until smooth. If it feels too wet, knead in a little flour and too dry, wet your hands a few times to knead in more water until it feels like the consistency of play dough. It shouldn’t stick to your hands or the countertop.
Cover the dough with a small bowl or wrap in plastic wrap and set aside for 30 minutes.Once rested, cut the dough into quarters and cover three quarters. Pinch off small pieces (about the size of a garbanzo bean (chickpea))
With a gnocchi board, using your thumb, gently press dwnwards and roll one of the small balls away from yourself to create a gnocchetti.Place onto a waiting sheet pan or board that's been generously floured. Continue this process until you run out of dough.
When you’re done, cover the Malloreddus with a tea towel. You can set these aside for up to 3 hours before cooking.
To make the sauce
Bring a large pan of generously salted water to a boil. Reduce the heat so that it’s gently simmering while you prepare the sauce.
Heat the oil in a large frying pan over a moderate heat until hot. Add the onion and garlic and fry for 1-2 minutes until soft. Add the sausage meat and break into small pieces. Let this fry for 3-4 minutes before adding the tomato and then the stock. Add salt & pepper then bring to a boil. Reduce the heat to low and simmer gently for 5 minutes, while you cook the pasta.
Turn the heat back up on the pasta water to bring back to a rolling boil. Tip in the gnocchi and cook for 3-5 minutes. The gnocchette will float to the surface. Cook for about a minute when this happens - it's actually pretty hard to overcook them so you don't need to be exact. Using a hand sieve or slotted spoon, fish out the Malloreddus and tip straight into the waiting sauce.
Add the rocket and carefully stir everything together until it's wilted a bit. Add a handful of Parmigiano Reggiano and 1-2 spoons of the pasta water to loosen the sauce, stirring well to mix everything. That’s it! You’re ready to portion up and serve.