In a skillet over medium-high heat, cook the ground beef until fully browned, breaking it into small pieces. Drain any excess grease and transfer the beef to the slow cooker.

Add the chopped onion, minced garlic, and sliced celery to the slow cooker. These vegetables will infuse the beef with a savory base as they cook.

In a small bowl, whisk together soy sauce, hoisin sauce, ground ginger, black pepper, and beef broth. Pour the sauce mixture over the beef and vegetables, stirring to ensure everything is well coated.

Cover the slow cooker with the lid and set it to low heat. Cook for 6 hours, allowing the flavors to meld and the vegetables to become tender.

About 30 minutes before serving, stir in shredded cabbage, julienned carrot, and water chestnuts. Turn the slow cooker to high to heat the fresh vegetables while retaining their crunch. Cook noodles or spaghetti according to the package instructions.

Serve the beef and vegetable mixture over the cooked noodles. Spoon plenty of sauce over each portion and garnish with chopped green onions or sesame seeds, if desired.