In a food processor, combine brown sugar, garlic, olive oil, cider vinegar, and chili pepper until smooth. Generously rub marinade over the ribs and refrigerate for at least 4 hours, preferably overnight.

In a medium saucepan, combine pineapple juice, red pepper flakes, mirin, and rice vinegar. Bring to a boil, then simmer for 30-45 minutes until thickened.

Preheat oven to 350°F (180°C) and prepare a baking sheet lined with parchment paper.

Place marinated ribs on the baking sheet bone-side down. Roast for about 2 hours, basting with glaze during the last 15 minutes.

Brush ribs with remaining glaze and broil for 3-5 minutes until crispy caramelized. Let rest before slicing.

Cut ribs into portions and serve with extra glaze for dipping.