From Food in Jars by Marisa McClellan
Makes 3 (1-pint/500mL) jars
4 lbs / 1.8 kg tomatillos, husked, washed, and finely chopped
1 cup finely chopped onion
3-4 jalapeno peppers, minced (seeds removed for a milder salsa)
8 garlic cloves, minced
1 tbsp ground cumin
2 tsp sea salt
1/2 cup lime juice
1/4 cup fresh cilantro, minced
Put jars in a large pot of water and bring to a boil.
Combine the tomatillos, onion, jalapenos, and garlic in a large pot. Bring to a boil, then reduce the heat and simmer 10 minutes. Add the cumin, sea salt, lime juice, and cilantro. If you prefer a smoother salsa, you can use an immersion blender to break down some of the salsa at this time.
Cook for an additional 10 minutes. Taste the salsa and add more salt, cumin, or lime juice if necessary.
Remove and drain jars from boiling water. Ladle the hot salsa into the prepared jars, leaving 1/2 inch of headspace. Wipe the rims, apply the lids and rings, and process in a boiling water bath for 15 minutes. When the processing time is up, remove the canning pot from the heat and remove the lid. Let the jars sit in the pot for an additional 5 minutes. This helps to prevent the salsa from reacting to the rapid temperature change and bubbling out of the jars. Make sure the lid has sealed before storing at room temperature.