Place chuck roast into a slow cooker. Add onion, carrots, brown sugar, soy sauce, garlic cloves, ginger, vinegar, sesame oil and red pepper. Cover and cook on High for 5 hours or on Low for 8 hours.
Uncover and remove the beef. Shred the beef into small pieces using 2 forks, discarding any fatty bits. Return meat to the slow cooker.
Add ramen to the slow cooker, submerging the noodles into the liquid and breaking them apart slightly if necessary. Cover and cook on high until noodles are tender, about 10 minutes.
Stir noodles to combine with the meat and stir in green onions. Serve, topped with Sriracha, sesame seeds and more green onions if desired.
