It depends on what it’s made of. If it’s still you can soak it in lye water, or use easy off oven cleaner. It’ll tear apart the burn spots in the organics and leave you with bare metal.

The tricky part, is if it’s aluminum. It’ll actually corrode the surface. All the organics will still come off of it, but it will leave a black oxide coating on the surface. Now to be fair that Black oxide coating is easier to scrub off then the original grease carbon, and polymers, but it will leave the surface a little thinner and a little pitted. If you do it more than a few times on thin aluminum you can actually put holes in it.

The next best thing to use would be bar keepers friend which is an oleic acid powder cleanser it requires quite a bit more elbow grease but it will get the job done without hurting the metal.