DIAGNOSIS The ceramic enamel (EasyClean) interior has absorbed grease and food spatter from normal use. The sticky residue is polymerized grease, not a damaged coating.
FIX Fill a microwave-safe bowl with 1 cup of water and 2 tablespoons of white vinegar or lemon juice. Microwave on High for 5-7 minutes until the interior is steamy. Let stand for 10 minutes. Wipe the interior thoroughly with a soft cloth or sponge. The steam will loosen the residue.
IF THAT DIDN'T WORK For persistent spots, make a paste of baking soda and water. Apply gently with a non-abrasive sponge, wipe, and rinse. Do not use commercial oven cleaners, steel wool, or abrasive pads.
HEADS UP This staining is cosmetic and does not affect cooking performance. Regular steam cleaning after messy spills prevents buildup.