Ingredients:
1) Preheat the oven to 180°C.
2) Cut the onions into half-moons and sweat in a pan with a dash of olive oil, bay leaf and salt. Over low heat, cook as much as possible without caramelizing. Add a little vinegar to give a sour touch and continue cooking until you get a syrupy or almost caramel consistency.
3) Brush the tartlet moulds with fat and pour in the flour, shake so that the whole surface of the mould is covered and tap to remove the excess.