How to clean a microwave with vinegar and salt?

You can clean with white vinegar & water (50/50) in a bowl. Place a toothpick in the bowl and heat for 5 - 10 minutes. Remove with mitts and wipe down. I'm unaware of needing salt. You can add baking soda (4 Tbsp in a quart of water), mix and wipe over interior, then the vinegar water.

Just vinegar and water in a bowl or cup heated to boiling. Keep the door closed and let the steam work for a few minutes to soften any greasy splatters and then remove the bowl or cup and wipe the interior well with a clean cloth. If you do this fairly often, no need for deep cleaning ever.

I use just plain water in a cup or bowl, bring it to a boil in the microwave and let it set with the door closed. Come back in 1/2 hour and wipe.

The steam does the work.

heat a cup of water -- should create enough moisture to just be able to wipe out the micro with a sponge ??

Here's a post that might help - https://chascrazycreations.com/natural-cleaning-with-vinegar/