Heat your grill – I like to use charcoal for this, but propane is fine also.
While grill is heating, prepare your vegetables to roast:
– Slice onions into ½″ thick slices
– Slice poblano and bell peppers into large flat pieces, Cut jalapenos in half.*
Brush peppers with olive oil, then grill everything until as “done” as you would like – personally, I like some dark grill marks for this, but not an overall char. If you have wood chips to smoke/grill with, use them – we used applewood chips. Remove items as they are ready – the peppers will cook the fastest. Allow everything to cool.
Turn your (oven) broiler up to high.
Prepare a couple cookie sheets with foil or parchment paper. Remove husks from tomatillos, wash well and remove any that don’t look fresh/good. Slice each in half, arrange in a single layer on baking sheets, toss garlic cloves in amongst the tomatillos. Roast under the broiler until as charred as you would like. Pour off excess juices, allow to cool, then puree in a blender or food processor.
Once everything is cool, chop up the peppers and onion (I use a food processor for this). Add all roasted vegetables to a large pot, along with tomatilloes, vinegar, lime juice & zest, sugar, and salt, stir well.
Heat to a boil, then reduce heat and simmer until liquid reduces a bit, and mixture reaches a consistency you like. Stir in the cilantro, if using, and cook for one more minute.
Ladle into hot, sterilized pint sized canning jars. Affix sterilized lids and rims, and process in a hot water bath for 15 minutes. (Add 5 minutes for altitudes above 1,000 feet; add 10 minutes for altitudes over 6,000 feet.) Allow to cool overnight.
Check all lids for a proper seal: they should have sucked down into a vacuum seal as the jars cooled. Store properly sealed jars for later use; refrigerate any that did not seal for use in the coming weeks.