The clever trick to cleaning your oven while you sleep

The steps:
1) First, preheat the oven to 80°C.

2) While heating, heat water in a saucepan.

3) When the oven is hot, turn it off.

4) Place a gratin dish filled with vinegar on the top plate. Next, add the pan of water to the bottom of the oven, then close the oven.

(You can also boil vinegared water directly and place it in the oven.)