Start with the garbage disposal. Sprinkle a couple of tablespoons of baking soda down the garbage disposal (without operating it) and squeeze the juice of one of your lemons (don't throw the lemon away). Close/seal the drain. Leave it and we'll come back to it later.
Now for the microwave. I will admit our microwave was gross, but in my defense, my husband is charged with cleaning the kitchen. Obviously, the inside of the microwave is not a high priority. (The lower left back corner is damaged, not dirty.)
Cut 3 lemons (including the one you just juiced) into small pieces (use all of the lemon, including the peel), and place them in a microwave-safe Pyrex dish. Fill with water and microwave 3 to 5 minutes until boiling hot. When it's done, don't open the door, but leave the dish in the microwave for 5 minutes. The hot water creates a steam that breaks down the crud on the inside of the microwave.
After 5 minutes, just wipe down the microwave with a damp cloth and voila!
I wasn't done with the hot water and lemons just yet. I filled my sink (the one that empties into the garbage disposal) with hot water, threw in a couple of tablespoons of baking soda and then dumped the hot water and lemon mix into the sink.
Let that sit for about a half hour, and you will find this disgusting mess. Lemons do a great job breaking down grease that might still be in your sink.
Did you think I forgot about the garbage disposal? For my last trick of cleaning three parts of the kitchen with three lemons, just open the drain with the sink full of lemon bits and turn on the garbage disposal as it empties. The baking soda and lemon juice you previously put in it should deodorize it a bit and with running the hot water and the lemons through will clean the blades.
How about that? Easiest cleaning I've done in a while! You can also use a lemon cut in half and some sea salt to scrub your wood cutting board - great deodorizer!
More lemon uses coming soon!