Boil the pasta in a large amount of heavily salted, rapidly boiling water, and cook it only until it reaches an al dente texture. Don’t add oil to the water, because this makes the surface of the pasta slick and prevents the dressing from clinging to it.
Avoid refreshing the pasta under running water. Doing so washes off the surface starch that causes the pasta to cling to its sauce or dressing, and also makes the pasta soggy. Instead, drain the pasta well, turn it out into a wide, shallow pan, and toss it with a little of its intended dressing so the pasta cools quickly and absorbs the flavorful dressing rather than plain water. (See food safety sidebar.)
Match the size and shape of the other ingredients to the size and shape of the pasta, just as you would when creating hot pasta dishes. Pasta salads prepared in this manner are pleasing to the eye and have a good mouthfeel.
While it’s thrifty to use leftover boiled pasta for pasta salad, keep in mind that cold pasta doesn’t absorb and bind with dressing very well. When using cold leftover pasta, plunge it into boiling water for a second, drain it, and then proceed.