Step 1: Prepare an ice bath. Fill a mixing bowl halfway with ice and enough water to cover it. Add about 1/2 tablespoon of salt for each quart of water (so you won’t wash away the salt absorbed during blanching).
Step 2: Blanch. Bring a pot of salted water to a boil and cook your vegetables to the desired tenderness.
Step 3: Shock. Using a slotted spoon, transfer the vegetables from the pot to the ice bath. Remove when they’re cold, in about 1 minute.