Louisiana Seafood Boil

INGREDIENTS

• 8 quarts water
• 1/3 cup canola oil
• 6 yellow onions, unpeeled
• 4 celery stalks, halved crosswise
• 2 lemons, unpeeled and quartered
• 12 garlic cloves
• 5 bay leaves
• 2-inch piece fresh ginger, thickly sliced
• Crab boil spice mix (see above) or 6 oz. packaged whole-spice crab boil
• 1/2 to 3/4 cup sea salt, or to taste
• 1 Tbs. cayenne pepper, or to taste
• 1 Tbs. black peppercorns, or to taste
• 2 to 3 lb. small red-skinned potatoes, unpeeled
• 24 live blue crabs or 4 to 6 small live Dungeness crabs
• 6 ears of corn, husked and halved crosswise
• 5 lb. large shrimp, with heads attached