To make the equivalent of a 32-oz. can of prepared nopalitos, start with 1 lb. of fresh nopales. To remove thorns, place each cactus paddle flat on a cutting board. Hold base steady and scrape away thorns with a sharp knife at a 45° angle, leaving intact as much of the green outer layer as possible. Repeat on the other side. Cut off base, trim any rough edges, and slice into 2" × 1⁄4" strips. They will be very sticky, so reduce "slime" by blanching nopalitos in a medium pot of boiling salted water for 3 minutes. Drain in a colander and rinse well with cold water. Bring a fresh pot of salted water to a boil, add nopalitos, and cook until tender, about 5 minutes. Do not overcook. Drain and use in place of canned nopalitos.