What You Need
Damp dish cloth
Plastic or silicone spatula
Empty the oven: Remove your oven racks, pizza stone, oven thermometer, and anything else you have inside the oven. Set aside.
Make a baking soda paste: In a small bowl, mix a 1/2 cup of baking soda with a few tablespoons of water. Adjust the ratio of both as needed until you have a spreadable paste. For me this took about 3 tablespoons of water to get the desired spreadable consistency.
Coat your oven: Spread the paste all over the interior surfaces of your oven, steering clear of the heating elements. I used gloves for this portion, as my oven was pretty grimy. It helped me really get in there and coat the dirtiest nooks and crannies without having to worry about all that grime under my nails. The baking soda will turn a brownish color as you rub it in; it also might be chunkier in some places than others, which is fine. Just try to coat the whole oven to the best of your abilities, paying extra attention to any particularly greasy areas.
Let it sit overnight: Allow the baking soda mixture to rest for at least 12 hours, or overnight.
Clean your oven racks: Meanwhile, clean your oven racks. See the full cleaning tutorial here.
Wipe out the oven: After 12 hours or overnight, take a damp dish cloth and wipe out as much of the dried baking soda paste as you can. Use a plastic or silicone spatula to help scrape off the paste as needed. I found that the damp cloth was enough for me, but a spatula might come in handy in those hard-to-reach places.
Spray a little vinegar: Put a little vinegar in a spray bottle and spritz everywhere you still see baking soda residue in your oven. The vinegar will react with the baking soda and gently foam.
Do a final wipe-down: Take your damp cloth and wipe out the remaining foamy vinegar-baking soda mixture. Repeat until all the baking soda residue is gone. Add more water or vinegar as needed while wiping to really get the oven clean and shiny.
Replace your oven racks: Replace the oven racks and anything else you keep in your oven, and you're done!