Combine brown sugar (or rock sugar, if using), soy sauce, rice vinegar, sesame oil, ginger, garlic and red pepper flakes in a small bowl.

Place cut, trimmed ribs into slow cooker.

Pour mixture over ribs and cook on low for 8-9 hours until meat is tender and falling off the bone.

Remove ribs from slow cooker and place on a plate and cover with foil to keep warm.

Skim fat from juices remaining in the slow cooker and transfer juices to a small saucepan.

Put cornstarch in a small bowl and add around 1/4 cup of the juices from the slow cooker, whisking to combine with the cornstarch.

Pour cornstarch mixture back into saucepan.

Bring to a boil, then reduce heat to a simmer until mixture thickens slightly.

Pour over ribs and garnish with scallions and sesame seeds. Serve immediately.

If you've never made ribs before, it's really important to trim your baby back ribs as directed here. I've made and eaten ribs without performing this essential step, and the flavor and tenderness difference is astounding. Trim your ribs, people. Trim your ribs.