Here is the formula:
Wipe down your microwave with water and a sponge (and a little dish soap if there are any troublesome spots)
In a microwave safe bowl, add 2 cups of water and approx. 4 tbsp. of baking soda. Microwave for 5 minutes.
Rinse out the baking soda/water mixture and add another 2 cups of water and 3-4 tbsp. of fresh lemon juice. Microwave for 5 minutes. (I figured lemon was good for a spring/summer scent. In the fall/winter try vanilla extract)
Wipe down the microwave one more time with water and a sponge.
(If the odor is still lingering.... put a little bit of baking soda in a small bowl and let sit for a couple hours or overnight. The baking soda should absorb the remaining odor)
An odor-free microwave!