Cut crayfish tails in half lengthwise. Season flesh of crayfish with salt and cayenne pepper, then brush with lemon juice and olive oil. Sprinkle with a few leaves of the herbs.
Place on a broiler pan and cook under a preheated broiler for 15 to 20 minutes, basting occasionally with a little olive oil.
When crayfish are lightly browned cooked, arrenge on a serving plate and garnish with watercress. Serve crayfish recipe with green salad and crusty bread.
