Combine the ground beef, onion flakes, garlic powder, Italian seasoning, salt, and black pepper in a large bowl, mixing just until combined.
Whisk the egg with the uncooked rice, then gently mix it into the meat. Form the mixture into ping pong–size meatballs.
Stir the crushed tomatoes, ½ cup of water, and the remaining Italian seasoning in the slow cooker, then add the meatballs.
Cover and cook on low for 4–5 hours or high for 3–4 hours, until the meatballs are cooked through, the rice is tender, and the internal temperature reaches 160°F (71°C).
Cover the slow cooker with the lid and cook on low for 4-5 hours or on high for 3-4 hours, or until the meatballs are cooked through and the rice is tender.
Stir the balsamic vinegar and basil into the sauce, adjust the seasoning, and serve hot.
Notes
Chef Jenn's Tips
Use lean ground beef for meatballs that are juicy but not greasy.
Don't substitute instant rice for long grain rice, as the cooking times and textures are different.
Feel free to customize the seasoning to suit your taste. Add a pinch of red pepper flakes for heat or swap out the Italian seasoning for your favorite herb blend.
Nutritional information for this recipe is provided as a courtesy and is calculated based on available online ingredient information. It is only an approximate value. The accuracy of the nutritional information for any recipe on this site cannot be guaranteed.