1. Warm oil in a large pot over medium-high heat. Sprinkle short ribs with salt and brown on all sides, turning with tongs, about 6 minutes total. Transfer to a slow cooker.
2. In a bowl, whisk hoisin sauce, 1/2 cup water, garlic and ginger. Pour over short ribs. Cover; cook on low until meat is falling off bones, 6 to 7 hours.
3. Stir in snow peas, cover and cook until warmed through, 5 to 10 minutes. Sprinkle with scallions and serve.