Prepare the Microwave: Remove any items from the microwave, but leave the glass tray and rotating piece inside.
Mix the Cleaning Solution: In a microwave-safe bowl or measuring cup, combine 1 cup of water, 1 cup of white vinegar (or the juice of 1–2 lemons), and throw the lemon rinds in too. Stir if using lemon juice.
Add a Safety Stick: Place a wooden spoon, chopstick, or skewer into the bowl to prevent superheating (which can cause a dangerous microwave explosion).
Steam It: Place the bowl into the microwave and heat on high for 5–10 minutes. The time will vary depending on how dirty your microwave is.
Carefully Remove the Bowl: Use oven mitts or potholders to take out the bowl. The microwave should be filled with steam, which will have loosened the grime.
Wipe Down the Inside: While the microwave is still hot, use a sponge, cloth, or paper towel to wipe down the interior surfaces (walls, vents, floor, and door).
Clean the Glass Tray: Take the glass tray and rotating piece out, clean them in the sink, wipe dry, and place them back in the microwave.