Mince and mash the anchovies, the garlic, and a pinch of salt to a fine paste and in a large bowl whisk together the paste, the mayonnaise, the yogurt, the scallions, the parsley, and the dill. In a saucepan of boiling salted water boil the pasta until it is tender and drain it in a colander. Rinse the pasta under cold water and drain it well. Add the pasta to the dressing, tossing it to coat is well, and stir in the tomatoes gently. Serves 2. Gourmet August 1993