Move your oven rack to the top and turn on the broiler.

Remove tomatillo husks. Place on a baking sheet along with the roughly cut onion.  Halve jalapeños and remove stem and seeds, then add to baking sheet.

Blister and char tomatillo, jalapeno and onion under the broiler – keep an eye on them, the timing really depends on your oven and you may need to move the pan around for even charring.

Working in batches (depending on the size of your food processor), puree charred items along with cider vinegar, extra-virgin olive oil, and a teaspoon of salt.

Adjust seasoning with salt and pepper.