Cook the spaghettini al dente in salted water, drain and set aside.
Heat plenty of olive oil in a high-walled pan. Put the peppers, onions, tomatoes, garlic, anchovy fillets and the olives in the oil and fry for 6-7 minutes, turning. Now add the pesto and season with the salt, pepper and sugar. Add herbs to taste. Add the prawns to the sauce and let them steep for a few more minutes.
Put the cooked spaghettini in the pan and mix with the sauce.