Wash the asparagus, peel the lower third and cut off the woody ends. Cut the asparagus into pieces. Peel garlic and onion and chop finely. Wash, clean and halve the tomatoes.
Prepare spaghetti in boiling salted water according to package instructions. Heat the oil in a frying pan. Sauté the asparagus in it. Add garlic and onion and fry briefly. Season with salt and pepper.
Deglaze with wine and 100 ml water, bring to the boil and cook for about 5 minutes. Add tomatoes and parmesan. Pour spaghetti on a sieve, drain and fold into the sauce. Wash parsley and cut into fine strips.
Arrange spaghetti on plates, sprinkle with parsley and parmesan slices.