Combine the brown sugar, vinegar, sambal oelek, fish sauce, lime juice, and garlic in a medium bowl, whisking to dissolve the sugar. Add the chicken, making sure each piece is covered. Season with salt and pepper.

Let sit for 30 minutes in the refrigerator. (This can be marinated for up to 24 hours in advance)

Preheat the oven to 425 degrees. Place the chicken, sauce and pineapple on a rimmed baking sheet lined with parchment paper.

Roast the chicken until deeply browned, and cooked through, 50-60 minutes. You may baste the chicken periodically while it is cooking.

Remove from the oven and scatter with the green onions, cilantro and sesame seeds before serving. Serve with a side of rice.