Lobster meat becomes tough and rubbery when it's overcooked. Since this recipe calls for cooked lobster, you don't want the perfectly cooked, tender lobster meat simmering in the soup or it will become overcooked in a matter of minutes. To avoid this, keep the cooked lobster meat separate in the refrigerator, then add it to each bowl and ladle the soup over top right before serving. The hot soup warms the lobster through without cooking it any further.