Peel and finely chop the onion. Halve the chilli pepper lengthwise, remove the seeds. Cut the pod into small pieces. Heat oil in a pan. Sauté onion and chili in it. Stir in tomato paste and sweat.
Add canned tomatoes and pour 75-100 ml of water. Season the sauce to taste with salt, pepper, possibly chilli and a little sugar and simmer over a medium heat for about 15 minutes. Prepare pasta in boiling salted water according to package instructions.
Wash and halve the tomatoes. Add cherry tomatoes to the sauce about 2 minutes before cooking. Drain the pasta. Wash and clean the rocket and put aside some rocket for garnishing. Coarsely chop the remaining rocket. Just before serving, add chopped rocket to the sauce and serve with the pasta.
Garnish with rocket and parmesan slices.