Buy commercially prepared thin ribbon noodles if you prefer.
Heat plenty of salted water in a large saucepan in which to cook the pasta.
Make the sauce: weigh the 1/4 lb arugula after removing the stalks, wash well, and dry in a salad spinner.
Pour boiling water onto the tomatoes in a bowl, wait 10 seconds, then drain and fill the bowl with cold water; drain again and peel, remove the seeds and any hard stalk sections, and chop the flesh coarsely.
Place the arugula leaves in the food processor with the garlic (use half a small skinned clove) and grated cheese; process just enough to chop finely, not to turn into a paste.
Turn into a mixing bowl, stir in the oil and the drained, chopped tomatoes.
Add a little salt and plenty of freshly ground pepper.
Add the pasta to the boiling salted water, stir then leave to cook for 3 minutes if fresh noodles are used; packaged pasta will take longer.
Drain when just tender, reserving 1/2 cup of the liquid.
Return the pasta to the saucepan, sprinkle with some of the reserved hot water so that it is very moist, and then stir in the sauce.