Why Your Pasta Needs Its Own Cooking Water
As pasta cooks it sheds starch into the water. That starch is the secret behind the glossy sauces you taste in Rome and Bologna; without it, sauce slides off the noodles instead of clinging to them.
A few rules: salt the water until it tastes like the sea, scoop out a half cup of starchy water before draining, and finish the pasta in the pan with the sauce, splashing in the reserved water as you toss. The sauce thickens, emulsifies, and grips every strand.
Try it with a simple aglio e olio. Toss al dente spaghetti with garlic oil and parsley, add a quarter cup of pasta water, and toss hard for ninety seconds. Three ingredients suddenly taste like a restaurant dish.