My grandfather's tip for cleaning the barbecue in 4 minutes flat

My grandfather told me this little trick one summer, when we were getting ready to put away the barbecue. I can still see him, calmly, taking out a sheet of aluminum foil, placing it on the hot grills... and a few minutes later, they were clean.

Here's how to do it, step by step:
Light your barbecue and let it heat up to about 260°C.
Unroll a sheet of aluminum foil (large enough to cover the grates).
Place it directly on the grill surface, matte side down.
Close the lid and let it sit for 4 minutes.
Once the time is up, open the lid, put on heat-resistant gloves if necessary, and remove the aluminum foil.