Marinate the beef: Put the beef in an airtight container and sprinkle it with the fish sauce, white pepper, black pepper, and brown sugar. Gently mix the seasonings into the meat until all the pieces are evenly coated. Then seal the container and refrigerate overnight.

Cook the dish: In a Dutch oven or cast-iron pot, combine the oil and garlic and cook over high heat, stirring frequently, just until the garlic is sizzling. Add the beef, stir to distribute the garlic, and use a wooden spoon to pat out the beef to cover the whole bottom of the pot. Cook without stirring for 2 minutes, stir, and cook for another 2 minutes, stirring frequently, until the meat is no longer pink.

Add ¼ cup water and reduce the heat to medium. Cook, uncovered, stirring every few minutes, until the beef is fork-tender or gives a little resistance when you pierce it with a sharp paring knife, 10 to 15 minutes.

Add the palm sugar and cook, stirring (breaking up the palm sugar, if that’s what you’re using), until the sugar is fully dissolved, 5 to 7 minutes.

Increase the heat to high. Add the salt and tamarind concentrate and cook, stirring, until the oil separates on top and the sauce coats the beef, about 5 minutes, depending on the size of your pot. Stir in the fish sauce and coriander. Cook for another minute or two to glaze the beef, then turn off the heat.

Tilt the pot so all the oil pools on one side, then use a spoon or ladle to scoop out the clear fat into a heatproof container or jar. Transfer the beef and dark-colored sauce to a plate or bowl and serve with white rice.