Rinse the dried oysters and soak them in 1 1/2 cups of hot water for 1 hour.

Drain the oysters, reserving 1 cup of the soaking liquid.

Soak the black moss in hot water to cover for 30 minutes and drain.

Heat a wok or wide frying pan over high heat until warm.

Add vegetable oil, swirling to coat the sides of the wok.

Add ginger, shallot, and green onion, and cook, stirring, for 30 seconds.

Add the oysters and stir-fry for 1 minute.

Add the reserved oyster soaking liquid and chicken broth.

Spread the black moss in an even layer over the oysters.

Reduce the heat to medium-low.

Cover the wok and simmer until the oysters are tender, about 30 minutes.

Stir in the sherry and sesame oil.

Add the cornstarch solution and cook, stirring, until the sauce boils and thickens.

Arrange the lettuce cups on a serving platter.

Spoon the oyster mixture into the lettuce cups.

Garnish with cilantro sprigs, if desired.

Serve immediately.