Using an oven broiler makes quick work of the roasting. It will take about 15 minutes. Once roasted, it is very easy to remove the skins from the peppers as well as most of the seeds. You could leave them in, just keep in mind the salsa will be much spicier.
1 pound tomatillos, husked and rinsed (6 medium tomatillos)
1 jalapeño pepper
1 serrano pepper
2 unpeeled garlic cloves
1/2 cup chicken or vegetable stock, see our chicken stock recipe
1/4 medium onion, chopped
1/3 cup loosely packed cilantro leaves and tender stems
1 tablespoon lime juice, or more to taste
1/2 teaspoon salt, or more to taste
Heat the broiler with a rack about 4 inches below the heat source. Place the tomatillos, jalapeño, serrano pepper, and garlic into a baking dish. Broil, turning occasionally, until they’re blackened in spots, 10 to 12 minutes.
Remove the baking dish and add chicken stock then use a wooden spoon to scrape any bits stuck to the bottom. Let tomatillos, peppers, and garlic cool.
When they are cool enough to handle, peel most of the skins from the peppers and remove seeds. For a spicier salsa, leave in some or all of the seeds. Remove the softened garlic from peel.
Add roasted tomatillos, peppers, garlic flesh, onion, cilantro, lime juice, and the salt to a food processor. Pour about half of the liquid from the baking dish then pulse 3 to 4 times or until the salsa is mostly smooth and no big chunks of tomatillo remain, scraping down the sides as necessary. Adjust with more liquid, lime juice, or salt based on consistency and taste.