Step 1

Pat 3–4 lb. English-style bone-in beef short ribs, cut into 3" segments, dry with paper towels; season with kosher salt on all sides. Heat a dry large Dutch oven or other heavy ovenproof pot over medium. Working in batches if needed, cook short ribs, turning occasionally, until browned all over, 8–10 minutes per batch. Transfer to a plate, leaving fat behind.

Step 2

Preheat oven to 350°. Bruise 4 lemongrass stalks, bottom third only, tough outer layers removed, with flat side of a chef’s knife and add to same pot. Add 2 large onions, finely chopped, 10 garlic cloves, finely grated, and one 3" piece ginger, peeled, finely grated, and cook over medium heat, stirring often, until onions are softened and becoming translucent, about 2 minutes. Cover pot and cook, stirring occasionally, until onions are golden, 8–10 minutes.

Step 3

Stir in 6 red or green Thai chiles or 2 large serrano chiles, thinly sliced, 6 makrut (Thai) lime leaves (if using), 2 Tbsp. light brown sugar, and 1 tsp. ground turmeric. Pour in three 13.5-oz. cans unsweetened coconut milk, ½ cup fish sauce, and 1½ cups water and bring to a simmer, stirring and scraping up browned bits with a wooden spoon. Nestle short ribs back into pot and return liquid to a simmer. Cover pot with a lid and transfer to oven. Braise short ribs until meat is tender and falling off the bone and liquid is thickened, 2½–3 hours. Fish out and discard lemongrass stalks and lime leaves, then stir in zest of 2 limes (if using) and ¼ cup fresh lime juice. Taste and season with more salt if needed.

Step 4

Divide steamed jasmine rice among shallow bowls and spoon short ribs over. Top with cilantro leaves with tender stems and chiles (if using). Serve with lime wedges.Do Ahead: Short ribs can be braised 2 days ahead. Let cool; cover and chill.