Place the beef stew meat, soy sauce, ginger, garlic, onion, carrots, and beef broth into a large freezer bag. Seal and freeze flat for later use.
When ready to cook, thaw the bag overnight in the refrigerator.
Transfer the contents to a slow cooker. Cook on low for 7 to 8 hours until the beef is tender.
In a small bowl, mix the cornstarch with 2 tablespoons of the cooking liquid until smooth. Stir the mixture back into the slow cooker.
Add the halved bok choy and sesame oil. Cook on high for 15 to 20 minutes until the bok choy softens slightly but still holds shape.
Serve the stew in bowls and top with sliced green onions.