3. Holding bag near bottom, gently pour crabs into boiling water (tongs don’t always give a steady grip) and cover pot. Cook, lowering heat to a simmer once water is boiling again: 15 minutes for 1½- to 2½-lb. crabs, 20 minutes for bigger ones.
4. Lift crabs out with tongs and rinse with cold running water until cool enough to handle.