Meanwhile, dice the tomatoes and chop 2 cloves of garlic and the chilli pepper. Briefly fry the garlic and chilli in a large pan in olive oil, then add the tomato cubes and cook for about 5 minutes. Add a dash of balsamic vinegar and let it simmer briefly.
Drain the spaghetti and toss in the sauce.
Peel and press the two remaining garlic cloves. Heat the olive oil in another pan. Fry king prawns and cloves of garlic in it. The king prawns should not be fried too long, otherwise they will become tough. The prawns are done when they no longer look glassy and curl up.
Roughly chop lemon basil (or basil if lemon basil is not available) and add to the spaghetti. Season to taste with lemon juice and possibly salt, pepper and olive oil. Serve with the fried prawns.