 So here's what you got to do. First of all, you want to soak the grids in hot soapy water because soaking them will definitely break up all of that baked on, caked on yuck. And then clean them with a nylon scrubbing pad. If the grills are really encrusted, you can use an oven cleaner in a well-ventilated area and then rinse clean. Next, you want to remove the lava rock or the ceramic briquettes and clean them with a wire brush and replace any that are deteriorated.