Start with our step-by-step canning how-to.

Sterilize four 8-ounce canning jars and lids.

Preheat the broiler. Put the poblano halves skin-side up on a foil-lined broiler pan with the onion and garlic. Broil until the poblano is charred and the onion and garlic are browned, about 8 minutes. Cool the poblano slightly, then peel.

Pulse the tomatillos in a food processor in batches until coarsely chopped, then transfer to a bowl. Add the poblano, onion and garlic to the processor and pulse until coarsely chopped (do not overprocess). Transfer to a large, wide saucepan. Add the cumin, lime juice, vinegar, sugar and 1 tablespoon salt. Bring to a boil over high heat and cook, stirring occasionally, until slightly reduced, 3 to 4 minutes.

Add the tomatillos and jalapenos to the pan, cover and return to a boil. Cook until heated through, 3 to 4 more minutes.

Fill the jars with the tomatillo mixture, leaving 3/4 inch headspace, then seal and process. After opening, top the salsa with cilantro, if desired.

Photograph by Charles Masters