Cut the tomatoes in half, remove cores. Squeeze out the seeds and chop. Place in a medium bowl and add the oil, garlic, basil. 1/2 teaspoon of the salt, and the pepper: mix well. (This sauce can be made ahead and left at room temperature for up to 2 hours).
In a large pot, heat 4 quarts of water to boiling. Add remaining 2 tablespoons salt, then the pasta and cook according to package directions, until the pasta is al dente (tender yet still firm to the bite). Drain the pasta and toss with the sauce. Stir in the mozzarella and toss again.