Combine marinade ingredients in a bowl. Add beef and stir to coat. Let stand for 10 minutes.
In the meantime combine glaze ingredients in a small bowl; stir until sugar is dissolved.
Place a stir-fry pan over high heat until hot. Add oil and butter; stir until butter melts. Add garlic, lemongrass, shallots and cook; stirring, until fragrant, about 30 seconds. Add beef and stir-fry, until it is seared on the outside and slightly pink in center, about 4 minutes.