Peel the garlic and cut into fine cubes. Clean and wash spring onions and cut into fine rings. Heat the oil. Steam garlic in it until transparent. Add tomato sauce and spring onions and bring to the boil.
Cook the pasta in boiling salted water according to the instructions on the packet. Wash the basil, shake dry and pluck the leaves from the stalks. Drain tuna and pluck into pieces. Drain the pasta and return to the pot, fold in the sauce and tuna.
Arrange on plates. Sprinkle with basil.