Heat the vegetable oil in a large frying pan. Gently brown the onions until a light coloration. It can take around 10 minutes. Add the thyme at mid-cooking.
Once the coloration is achieved, pour the ice cider, add salt and pepper. Cook for another 2 to 3 minutes. Leave it to cool.
Cut the brie cheese in small dices. Place them in the mini tartlets and bake in the oven 5 minutes at 300ºF until the cheese has melted.
Add the caramelized onions on the top and bake again for 5 minutes. Serve hot.
Serving Size 8