- Combine 1 cup water and lemon, lime or orange slices (squeeze juice from the fruit slices into the water) in a microwave-safe bowl. Or, if you have white or apple cider vinegar on hand, combine a few tablespoons and 1 cup water in a microwave-safe bowl.
2. Place the bowl in the microwave and turn it on high power for several minutes until the mixture boils and the window steams up.
3. Let cool for 5 minutes before opening the door, then remove the bowl and wipe the inside clean with a sponge.