X Research sourceStep 2, Thaw a frozen crab. If you are using frozen crab, thaw it out before cleaning it. 4 Rinse under cool water. After your crabs have been drained, run cool water over them. … Then, remove the crab from the ice water and lay it on its back. Then, use tongs to remove the crab from the water and place it in an ice bath to cool. If you purchased a live crab, it is necessary to kill it before cooking it. If you’re using a live blue crab, submerge the crab in a large bowl of ice water for 2-3 minutes to stun it. Remove the crabs from the pot and let sit until cool enough to handle. Step 1, Kill the crab first, if necessary. Use a knife or ice pick to stab the crab through its shell 1 inch (2.5 cm) below its mouth… Set a steamer basket in the pot and the crabs in the basket or, if you have a lot of crabs, simply pile them in. The simplest way to kill a live crab is to immerse the crab in boiling water for 60 seconds. Once cooks, pour the pot of water over a colander to drain the crabs. Cover the pot and steam until the crabs are cooked through, 10 minutes for small blue crabs and 15 for larger Dungeness and up to 20 minutes for even bigger crabs.