Remove the grates from the stovetop
Let the grates cool completely
Soak the grates in hot, soapy water
Scrub with a non-abrasive sponge or brush
Use a paste of baking soda and water for stuck-on residue
Let the paste sit for 15 to 30 minutes
Scrub again until clean
Rinse thoroughly with clean water
Dry completely with a towel
Reinstall the grates only when fully dry