This is a common way to quickly cook asparagus to perfection and serve it cold in salads or as a luncheon side dish. If you'd prefer to serve the asparagus warm, skip the ice water bath. Here's how to blanch asparagus: 1  Boil a large pot of water and 2 teaspoons of salt. 2  Place the asparagus in the water and let it cook for 2 1/2 - 3 minutes. 3  Test an asparagus spear for doneness-it should still be crispy, not limp.