Cut the red pepper into large chunks along with the shallots and garlic. Place in a large roasting tray.
Sprinkle the brown sugar and balsamic vinegar over the peppers.
Pull the thyme leaves from their stalks and toss over the peppers.
Roast in the preheated oven for 20 minutes until the peppers are just starting to charr and the brown sugar and balsamic are starting to caramelise and bubble.