For the tagliatelle with vegetables, chili and arugula, bring a pot of water to a boil. In the meantime, chop the chili with the garlic and sauté with the chopped onion in a deep pan with olive oil.
Chop the rest of the vegetables, except for the arugula, add them to the pan and saute. Add a little (about 4 tablespoons) water and simmer.
Season with salt and pepper. Cook the tagliatelle in water until al dente, then drain and fold into the vegetable mixture.
Season everything again to taste. Serve sprinkled with arugula and parmesan.