The easiest way to make these slow-cooked eggs is actually just to include 6-8 eggs at the very top of your Hamin or Chulent. After all the ingredients have been added, top the pot with your eggs and add enough water to make sure that the eggs are covered.
If you want to make parve huevos Haminandos, you will need some forward planning. For 12 eggs you need the skins from 12 onions, collect them throughout the week and keep them in a paper bag to make sure that they don’t get moldy.
A minimum of 12 hours before you want to serve them, start by placing the onion skins, at the bottom of a large heavy-bottomed pot with a tight-fitting lid, alternatively you can do this in a slow-cooker. Place the eggs on the onion skins, the skins will not only color the eggs and add flavor they will also help keep them from braking. Top with enough water to cover the eggs and onion skins by more than 2 inches, add two tablespoons instant coffee granules and a tablespoon of vegetable oil.
Cover tightly with the lid and cook in an oven set at 100℃ (200℉) for 12 hours, alternatively cook in a slow cooker set at low for at least 12 hours.
My friend Bracha takes these velvety eggs out of the overnight cooking liquid on Shabbat morning and while still warm she mashes them and adds very finely chopped onion, oil, salt, and pepper to make one of the best egg salads ever.