Haul out your biggest pot, fill it with water and bring it to a boil. Then add 1/2 cup of BAKING SODA….VERY SLOWLY!
Literally, you have to add it about a tablespoon at a time because it IMMEDIATELY fizzes up quite alarmingly! (The fizz goes right away.)
Then take your caked-with-grease filter and submerge it in the pot. (Well, 1/2 of it anyway.)