In a small bowl whisk the mayonnaise, buttermilk, lemon juice, and dill weed until smooth, set aside.
Drain and rinse the cooked pasta in cold water, and drain again. Add the pasta to a large bowl.
Add the chopped vegetables to the pasta bowl, and pour over the dressing. Stir until the dressing has coated the pasta and vegetables. Refrigerate for at least 2 hours before serving.
If you need to make this the night before, don't chop or add the tomatoes until the day you want to serve. They get mealy in the fridge.Nutritional values are approximate. Please use your own calculations if you require a special diet. The values below are for 1/10 of the recipe.