In a medium bowl, mix together the oyster sauce, fish sauce, grated garlic, and ginger until well combined. Coat the beef steak thoroughly with this marinade. Allow it to marinate for at least 30 minutes at room temperature, or up to two hours in the fridge.

In a dry skillet over medium heat, toast the glutinous rice until golden brown for about 4-5 minutes. Grind the toasted rice into a coarse powder. In a bowl, combine this rice powder with fish sauce, lime juice, tamarind paste, evaporated cane sugar, chili flakes, and chopped cilantro and scallion, mix until the sugar dissolves.

Preheat a grill pan over medium-high heat for about 5 minutes. Add the marinated beef steak to the pan, grilling each side for approximately 2.5 minutes, turning the steak 90 degrees halfway through for crosshatch marks.

Once the beef is grilled to your liking, transfer it to a cutting board and allow it to rest for 10 minutes. Then slice the beef thinly against the grain.

To serve, place the sliced beef on a platter, sprinkle with white pepper and toasted rice powder, and accompany with cool vegetables and Nam Jim Jaew sauce.