1. Preheat the oven to 175°C, gas mark 4.
2. Mix the brown sugar, rice vinegar, black pepper and syrup in a small bowl.
3. Place the bacon slices on an oven grilling rack and set over a baking tray.
4. Bake the bacon in the preheated oven for 10 minutes. Turn the slices, and bake for another 5 minutes.
5. Remove the bacon and brush both sides with the brown sugar mixture. Return the bacon to the oven and bake for another 5 minutes. Repeat the basting and baking twice more or until the bacon is browned and crisp. Keep aside until needed.
1. Heat the olive oil in a large frying pan.
2. Add the onions and pinch of salt. Cover with a lid and cook over medium-low heat for 12-15 minutes, or until tender, stirring occasionally.
3. Remove the lid and continue to cook over medium heat for 3-5 minutes, or until golden, stirring frequently.
4. Add the balsamic vinegar and cook over a medium heat until the liquid evaporates. This will take about 1 minute. Then season with salt and pepper and remove from the heat. Keep warm until needed.
5. Grill the burgers, until they are cooked through. Lightly toast the brioche buns and then assemble: place a burger on the bun, then cheese, a second burger, a second layer of cheese, the candied bacon and onions then top with lettuce, tomato and French’s Classic Yellow Mustard.