Beat the egg in a large mixing bowl. Add the rest of the ingredients except the lettuce and the cheese and whisk to combine.
Cut the stems off the heads of Romaine and fan out the lettuce on a serving platter. Sprinkle the Parmesan over the lettuce and drizzle the dressing on top. Serve immediately.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.