Creating Slow Cooker Salisbury Steak Meatballs can be straightforward if you follow these simple steps:

1. Prepare the Meat Mixture: In a large bowl, combine the ground beef, breadcrumbs, egg, chopped onion, minced garlic, Worcestershire sauce, salt, pepper, onion powder, and garlic powder. Mix until well combined.
2. Form Meatballs: Shape the mixture into meatballs, about 1 inch in diameter. Set aside.
3. Make the Gravy: In a separate bowl, whisk together the cream of mushroom soup, beef broth, soy sauce, and Dijon mustard until smooth.
4. Add Meatballs to Slow Cooker: Place the meatballs in the slow cooker. Pour the gravy mixture over the meatballs, ensuring they are submerged.
5. Cook: Cover the slow cooker and cook on low for 6 to 8 hours or on high for 3 to 4 hours. Make sure the meatballs are cooked through.
6. Thicken Gravy (Optional): If you prefer a thicker gravy, mix cornstarch with a little cold water to create a slurry. Stir it into the gravy about 30 minutes before serving.
7. Check for Doneness: Ensure the meatballs reach an internal temperature of 160°F (70°C).
8. Garnish: Before serving, sprinkle fresh parsley on top for added color.

These steps will guide you in preparing this mouthwatering dish effortlessly.