Preheat the oven to 180 °C/ 355 °F (conventional), or 160 °C/ 320 °F (fan assisted).

Heat the oil in a frying pan over medium heat. Add the onions, and cook, stirring occasionally until the onions start to soften, around 12-15 minutes.

Lower heat, add vinegar, sweetener and salt, and cook, continuing to stir occasionally, until dark and caramelised.

While the onions are cooking, press the pie crust into 12 greased muffin tins. Tip: Instead of 12 mini tartlets you can make 1 large tart.

Bake 10 minutes, and then remove and allow to cool slightly. Once cooled slightly, divide the onions evenly among the tart cases.

Chop the brie into 12 even pieces, and top the onion. Scatter with the herbs.

Bake for 15 minutes or until the brie has softened and the tops are starting to brown.

Serve immediately or store in the fridge for up to 5 days. To serve, gently reheat in the oven or eat cold.

Preheat the oven to 180 °C/ 355 °F (conventional), or 160 °C/ 320 °F (fan assisted).

Heat the oil in a frying pan over medium heat. Add the onions, and cook, stirring occasionally until the onions start to soften, around 12-15 minutes.

Lower heat, add vinegar, sweetener and salt, and cook, continuing to stir occasionally, until dark and caramelised.

While the onions are cooking, press the pie crust into 12 greased muffin tins. Tip: Instead of 12 mini tartlets you can make 1 large tart.

Bake 10 minutes, and then remove and allow to cool slightly. Once cooled slightly, divide the onions evenly among the tart cases.

Chop the brie into 12 even pieces, and top the onion. Scatter with the herbs.

Bake for 15 minutes or until the brie has softened and the tops are starting to brown.

Serve immediately or store in the fridge for up to 5 days. To serve, gently reheat in the oven or eat cold.