Sear the beef: Pat the beef dry. Heat 2 tablespoons neutral oil, for searing in a large Dutch oven over medium-high heat and sear 4 pounds beef sirloin tips, cut into 2-inch chunks in batches until browned on all sides. Transfer to a plate.
Build the aromatics: In the same pot, sauté 0.5 medium onion, chunked, 8 garlic cloves, smashed, and 2 tablespoons fresh ginger, grated for 2 minutes until fragrant, scraping up the browned bits.
Make the braising sauce: Stir in 0.75 cups soy sauce, 3 tablespoons brown sugar (or honey), 3 cups beef broth or water, 1 Asian pear or apple, grated (optional, tenderizes and sweetens), 1 tablespoon gochujang (optional, for a little heat), and 0.5 teaspoons black pepper. Return the beef to the pot and bring to a boil.
Braise the beef: Reduce to a low simmer, cover, and cook until the beef is starting to turn tender.
Add the vegetables: Add 4 carrots, cut into thick chunks, 1 pound potatoes, cut into large chunks, and 1 pound sweet potatoes, cut into large chunks, pushing them into the liquid. Cover and simmer until the vegetables and beef are fork-tender and the sauce has thickened slightly.
Finish and serve: Stir in 1 tablespoon toasted sesame oil and taste, adjusting with more soy or sugar. Serve hot over rice, topped with 3 scallions, sliced, for serving.