Phat Sii Krong Neua

Name: Phat Sii Krong Neua
Ingredients: 4 garlic cloves; 1 Tbsp. finely chopped cilantro root or stem; 3 Tbsp. oyster sauce; 2 Tbsp. fish sauce; 2 tsp. freshly ground white pepper; 2½ lb. ¼–½-thick crosscut bone-in beef short ribs (flanken-style); Kosher salt; ¼ cup oyster sauce; 1 Tbsp. fish sauce; 1 tsp. freshly ground white pepper; 3 Tbsp. vegetable oil; 1 sweet onion, thinly sliced; 4 garlic cloves, smashed; 2 red Thai chiles, thinly sliced; 4 scallions, sliced into 1 pieces; 1 cup Thai basil leaves; Cooked jasmine rice (for serving); A mortar and pestle