Scoop the onions into a glass or stainless bowl. Cover with very hot tap water. (The water should be steaming; if yours isn’t heat it a little on the stove.) Let stand 20 minutes, then drain. Sprinkle with 1 teaspoon salt. Cover with the lime juice and lay a plate on top to keep them submerged. Cover the bowl and refrigerate 3 or 4 hours (or, preferably, overnight). Scoop the onions into a storage container, cover and store in the refrigerator for up to a month or more. After a few weeks, the texture of the onions will begin to deteriorate.
Variations on the theme: As with the recipe here some habanero can be pickled with these onions, though it’s not that common in the Yucatan with an habanero salsa would be served alongside. A little Mexican or Yucatecan oregano could be added, and I sometimes like a little black pepper—but that’s just me.
Do you want the texture to change or should they be used before it changes? Can’t wait to try these. Going to make the mole and I am excited!