Remove the glass turning plate from inside the microwave. Submerge the glass carefully inside a sink filled with hot, soapy water, and wash the burnt food off with a cloth. Rinse with water, and wipe it with a towel until dry.
Fill a bowl safe for microwave use with white vinegar, and do not dilute the vinegar. Or substitute the vinegar for a bowl filled with equal parts water and lemon juice.
Sit the bowl filled with white vinegar or lemon juice and water inside the microwave, and then close the door. Cook the liquid on high for 5 to 10 minutes until it begins to boil.
Leave the bowl sitting inside the microwave for 20 minutes before continuing. Remove the bowl from inside the microwave, and then dampen a sponge with the contents in the bowl.
Scrub the inside of the microwave clean with the damp sponge. Use a paper towel dampened with water to rinse the microwave, and wipe it dry with several fresh paper towels.