On a grill set to high heat, roast the poblano peppers until charred- about 5-7 minutes. Set aside in a bowl, cover with plastic, and let cool until you can handle them. Remove the stem, peel the skin of the peppers, remove any membranes and seeds, and discard. Rough chop the inner pepper flesh, now softened from roasting, and place into a food processor.
Meanwhile, remove husks from tomatillos and rinse to remove sticky substance from the skins. Slice in half- like a bagel. In a large skillet lined with foil, place tomatillos cut side down, throw in whole jalapeños, and 3 cloves of garlic with the skin on. (see photo) Roast on medium-high heat until charred and juice begins to render from the tomatillos- about 5-7 minutes. You can also place the vegetables in a pan under a boiler, but watch carefully so that the garlic does not burn.
Place roasted tomatillos in the food processor with the poblano peppers. Remove skin from garlic, and toss in with peppers. Remove and discard the stem from jalapeños. Cut jalapeños in half length-wise and remove membranes and seeds. Rough chop and add to food processor reserving a few pieces for garnish.
Finally, add lime juice, canned green chilies, and cilantro (optional) to the food processor and pulse 4-6 times until the salsa is chopped, but not completely pureed. I like a bit of texture to my salsa- so do not over-process. Add salt to taste. Stir in chopped onion and cumin. Top with reserved jalapeño.
Pour into a serving bowl or store in the fridge (covered) for up to 4-5 days.