Add the beef stew meat, onion, carrots, ginger, garlic, soy sauce, and beef broth to the slow cooker. Stir to combine.
Cover and cook on low for 7 to 8 hours until the beef is tender.
In the last 30 minutes of cooking, stir in the bok choy.
Mix the cornstarch with 2 tablespoons of water, then stir the slurry into the stew to thicken the broth.
Serve the stew in bowls topped with the sliced green onions.