Combine the garlic, whiskey, soy sauce, oyster sauce, fish sauce and sugar in a mixing bowl. Mix well to dissolve the sugar. Add the beef and toss until well coated, then cover and leave to marinate for 30 minutes. Meanwhile, arrange the salad on a serving platter.
Heat a wok or frying pan until smoking hot. Add the vegetable oil and wait until it smokes. Add the beef and toss for no longer than 1 minute, taking care as flames will rise. Add a pinch of freshly ground black pepper, then arrange the beef over the salad.
Serve immediately, garnished with frangipani or marigold petals, if desired.