To the slow cooker, add the chicken bones, onion, ginger, coriander seeds, cloves, star anise, sugar, fish sauce, and cilantro stems. Fill with water to the max level of your slow cooker. Turn slow cooker to high for 4-6 hours or low for 8-10 hours.
Remove all chicken and cilantro stems, strain broth through cheesecloth. Taste and adjust with additional fish sauce and sugar if needed.
Soak rice noodles in cool water for 5 minutes. Drain.
In the meantime, bring a big pot of water to a boil. Add the chicken slices and let cook for 1-3 minutes or until cooked through.
Remove the chicken slices. Next, add the rice noodles to the water and cook for 1 minute. Remove noodles and divide amongst 4 serving bowls.
Fill each bowl with chicken slices, bean sprouts, cilantro leaves, red onions and broth. Serve with lime, Sriracha, and hoisin at table as condiments.
