Add the beef stew meat, potatoes, carrots, onion, garlic, and ginger to the slow cooker.
Pour in the soy sauce and beef broth, then sprinkle with black pepper. Stir gently to combine everything.
Cover and cook on low for 7 to 8 hours until the beef is fork-tender.
In a small bowl, whisk the cornstarch with 2 tablespoons of cold water until smooth.
Stir the cornstarch mixture into the stew and cook on high for 20 more minutes until the gravy thickens.
Ladle into bowls and top with sliced green onions before serving.