Preheat your oven to 325°F (160°C). Pat the short ribs dry with paper towels and season generously with salt and black pepper.

Heat the avocado oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Working in batches, sear the short ribs on all sides until deeply browned, about 2-3 minutes per side. Transfer the seared ribs to a plate and set aside.

Reduce the heat to medium. Add the chopped onion to the pot and cook until softened, about 5-7 minutes, scraping up any browned bits from the bottom of the pan.

Add the minced garlic and grated ginger to the pot and cook for another minute until fragrant.

Pour in the beef broth, soy sauce, brown sugar, and rice vinegar. Bring the mixture to a simmer, stirring until the brown sugar has completely dissolved.

Return the seared short ribs to the pot, nestling them into the liquid. The liquid should come about three-quarters of the way up the ribs. Cover the pot and transfer to the preheated oven.

Braise for 2.5 to 3 hours, or until the meat is fork-tender and falling off the bone.

Carefully remove the cooked short ribs from the pot and set them aside. Skim any excess fat from the surface of the braising liquid. Bring the liquid to a simmer over medium heat on the stovetop. Whisk in the cornstarch slurry and simmer for 2-3 minutes, until the sauce has thickened into a glaze. Stir in the sesame oil.

Serve the short ribs immediately, spooning the extra glaze over the top. Garnish with sliced green onions and sesame seeds.

Follow steps 2-5 on the stovetop. After the sauce is made, transfer it and the seared ribs to a slow cooker.

Cook on LOW for 6-8 hours or on HIGH for 4-5 hours, until the meat is tender.

Remove the ribs and transfer the cooking liquid to a saucepan. Follow step 8 to thicken the glaze on the stovetop before serving.