Gratin of Spider Crab

• 4 spider crabs
• 4 tablespoons olive oil
• 1 medium onion, finely chopped

Boil the crabs in water for 15 minutes. Meanwhile, heat the oil in a large saucepan and sweat the onion, garlic and leek for about 10 minutes.

Remove the crabs from the boiling water and put on one side, upside down, until they are cool enough to handle. Then remove and discard the long, spindly legs and crack the bodies open to remove the crab meat.

Add the tomatoes, tomato pur