Season all sides of the short ribs liberally with salt and pepper. Brown the outside of the short ribs in a pan and place them in the bottom of the slow cooker.
In a food processor or blender, combine the apples, vinegar, soy sauce, garlic and scallions. Process until the mixture is well combined and thick. Pour evenly over the short ribs.
Cook on low for 6 hours or until the short ribs are fully cooked and tender. Serve with additional apple slices.
Notes
If you increase the amount of short ribs, increase the cooking time by 1-2 hours. Modified from Nom Nom Paleo and Gourmet Girl Cooks.