Place the beef chunks, onion, ginger, star anise, cinnamon stick, and cloves into the slow cooker.
Pour in the beef broth, fish sauce, and brown sugar. Stir once to combine.
Cover and cook on low for 8 hours until the beef is very tender.
About 20 minutes before serving, cook the rice noodles in a large pot of boiling water according to package directions. Drain and divide among four bowls.
Remove the beef from the slow cooker and slice or shred it. Strain the broth if desired to remove solids.
Ladle the hot broth over the noodles and beef in each bowl. Top with cilantro and Thai basil. Serve with lime wedges on the side.