Choose a large saucepan and fill it with enough cold water to cover the crab. Add coarse sea salt (about 60-80 g per litre of water) and bay leaves.
If the crab is still alive, place it in the cold water before heating; if it's already dead, wait until the water reaches a rolling boil before adding it.
Once the water returns to a boil, cook the crab for 18-20 minutes if it weighs 1-1.5 kg.
Turn off the heat and leave the crab in the cooking water for a few minutes to deepen the flavour, or transfer it to a bowl of iced water to stop it cooking.
Serve the crab cold or at room temperature. Remove the top shell, discard the gills and pick out the meat from the legs and body. Serve with lemon wedges or a light vinaigrette.