Measure four cups of cold, clean water into a microwave-safe baking dish that will fit on the microwave tray.
Squeeze the juice of one lemon into the water and add a cinnamon stick or 1 tsp. ground cinnamon. Stir the mixture with a wooden spoon to combine the ingredients.
Cover the baking dish with microwave-safe plastic wrap. Using the tines of a fork, make five puncture marks in the plastic wrap, evenly spaced over the top of the baking dish.
Place the baking dish in the microwave and set the platter to rotate if possible. Bring the water to a boil on a high setting for 10 minutes without opening the microwave door.
Open the microwave door carefully with oven gloves or a kitchen towel to prevent the steam from burning you. After the steam has dissipated, make sure that there is still water in the baking dish.
Reduce the microwave setting to low and continue heating the water for an additional 10 minutes.
Remove the baking dish from the microwave and allow the water to cool at room temperature for one hour. Discard the plastic wrap and water mixture.
Wipe the entire inside of the microwave and microwave door with clean paper towels to remove the moisture.