Combine sherry and soy sauce in a small bowl. Set aside.
Heat oil in a large wok or heavy skillet over high heat until hot but not smoking; add shallot and ginger, and stir-fry 1 minute or until shallot begins to soften. Add lettuce, and stir-fry 1-2 minutes or until it just begins to wilt.
Swirl in sherry mixture, salt, sugar, and pepper, and continue to stir-fry 30 seconds or until lettuce is just tender and still bright green. Serve immediately.