Peel and chop the garlic. Clean and wash spring onions and cut into fine rings.
Heat the oil in a pot. Sauté the garlic and spring onions in it. Add the chopped tomatoes, bring to the boil, cover and simmer for about 5 minutes.
Cook the pasta in plenty of boiling salted water for about 10 minutes until al dente. Wash the basil and remove the leaves.
Season tomato sauce with salt and pepper. Drain the tuna, divide into bite-sized pieces and add to the sauce. Drain the pasta and put it back into the pot. Mix with the tuna and tomato sauce and arrange on plates.
Sprinkle with basil leaves.