01 - Season beef cubes thoroughly with kosher salt and black pepper, ensuring even coverage on all sides.
02 - Heat vegetable oil in a large Dutch oven over medium-high heat. Working in batches to avoid overcrowding, sear the beef until deeply browned on all sides. Remove browned beef and set aside.
03 - In the same pot, add onion, lemongrass, garlic, ginger, and red chilies. Sauté for 3-4 minutes until fragrant and onions are softened, scraping up any browned bits from the bottom.
04 - Stir in fish sauce and brown sugar, cooking for 1 minute to allow the sugar to dissolve and flavors to meld.
05 - Return the seared beef to the pot. Add coconut milk, beef broth, and carrots. Bring the mixture to a gentle simmer, stirring to combine all ingredients.
06 - Reduce heat to low, cover tightly, and braise for 1 hour to begin tenderizing the beef.
07 - Add quartered mushrooms, stir gently to incorporate, and continue braising covered for another 1 to 1.5 hours until beef is fork-tender and sauce has thickened slightly.
08 - Remove and discard lemongrass stalks. Stir in lime zest and juice. Taste and adjust seasoning with additional salt or fish sauce if needed.
09 - Serve hot, generously garnished with chopped fresh cilantro, sliced scallions, and additional lime wedges on the side.