While it is not necessary to precook tomatillos before turning them into salsa, roasting them first imparts just a hint of smoky flavor and makes the salsa more flavorful. You can add more peppers or vary the type of peppers if you like things extra spicy. As is, this salsa is mild.
2 pounds tomatillos
1 small-to-medium white onion
2 fresh Anaheim peppers (or jalapeño, if you prefer more spicy)
Remove husks from tomatillos and cut in half. Trim ends off peppers and cut in half. Remove the seeds unless you like things very spicy.
Place tomatillos and peppers cut side down on a baking sheet and broil until skins are charred and bubbling. Remove and place in a covered glass bowl until cool enough to handle. This step helps soften the skins and makes them easier to remove. Scrape off charred skins. Don’t worry if you cannot remove all of the skin.
Cut the onion in large pieces. Place the onion, garlic, lemon juice, cilantro (if using), roasted tomatillos, and peppers in a blender container. Blend until finely chopped. If you prefer your salsa chunky, blend less. Salt to taste. Stir in water kefir or whey.
Place in a 2-quart mason jar and cap tightly. An airlock lid works well for this. Let ferment at room temperature for 3 days before moving to the refrigerator or other cool storage.