Put the pasta in boiling water, add salt and cook al dente according to the instructions on the packet.
Remove the stalk from the fresh San Marzano tomatoes and roughly cut them into smaller pieces. Then put in a hot pan and simmer to allow the liquid to evaporate. Peel and chop the garlic clove and onion and add to the pan. Add the olive oil, tarragon, basil, salt, pepper, the grainy cream cheese and a dash or two of lemon juice and stir. After a total of 15 to 20 minutes, most of the tomato juice should have evaporated and the sauce should have thickened a little.
Drain and drain the pasta. Pour the sauce over the rigatoni, mix and serve on the plates with a little parmesan.
The tomato variety is also available from a can, e.g., from Mutti. Regular canned tomatoes also work, but they are not as aromatic.