Bring a large pot of salted water to a boil and carefully plunge lobsters head first into the pot.

Sprinkle in the parsley and lemon peel, and bring pot back to a boil.

Boil lobsters for 6 minutes.

Transfer lobsters with tongs to a bowl and pour 1 cup of cooking liquid over them.

Allow lobsters to cool.

Crack the claws, and cut through the underside of the tail, remove meat in large pieces.

Halve the tail meat lengthwise and discard the black vein that runs the length of the tail.

Lift out the tomalley liver, which is khaki colored, and the coral eggs if the lobsters are female.

Combine the tomalley and coral with mayonnaise and 2 Tbsp. of the cooking liquid, season to taste with sea salt and pepper, whisk until smooth.

To serve: Arrange the butter lettuce leaves on 2 plates and divide the lobster meat between the plates. Sprinkle the diced tomatoes and cucumbers around the edge of the plates and serve the lobster mayonnaise in small bowls on the side.

Serve immediately.