Put a large pot of water on to boil.
Combine tomatoes, vinegar, garlic and salt in a large bowl. Set aside to marinate.
Cook pasta according to package directions. Reserve ½ cup pasta water, then drain. Immediately return the pasta to the pot. Add fontina and the reserved cooking liquid; stir constantly until the cheese is melted. Fold in ricotta. Transfer to a serving bowl or individual pasta bowls.
Using a slotted spoon, spoon the marinated tomatoes over the pasta. (Discard the marinating liquid.) Drizzle with oil and top with basil and a generous grinding of pepper.
