Preheat the oven to 425 ℉. You can lightly coat your baking sheets with a bit of pan spray or a very thin coating of oil if they are not nonstick, or line them with parchment, for easier cleanup.

Wash the tomatoes and onions. Peel the garlic and set aside.

Using a small, sharp paring knife or strawberry huller, core the tomatoes, removing just the stem and any hard white or green fibrous bits. Spread the tomatoes out on a half sheet pan or other shallow baking pan.

Trim the root end from the onions and cut them into wedges. Spread them out on another baking sheet.

Roast the tomatoes and onions in the preheated oven for about 25 minutes.

Put a kettle of water on to boil for the chiles.

Check the sheet pans about halfway through, and then periodically, giving them a shake to loosen the vegetables from the pans or turn them with tongs if they’re sticking. You may also want to rotate the pans on your oven racks so that they cook evenly.

Toast the dried chiles lightly in a heavy pan on a medium flame. Just heat them a few seconds on each side, or until they are fragrant and beginning to puff up. Don’t burn them or they’ll be bitter. Let them cool.

Remove the stems and seeds from the dried chilies, tearing them into large pieces. Pour the boiling water over the chiles, stirring them to submerge all the pieces. Let the chilies soak and rehydrate, reserving the liquid.

Roast the vegetables until they are beginning to soften. The tomato peels will begin to split and char, and the onions will soften and become translucent.

Remove the pans from the oven and set the pans aside until they are just cool enough to handle.

While the tomatoes are cooling enough to peel, fill your canner with enough water to cover the tops of the jars by at least one inch, cover the pot, and bring up to a boil.

Wash and sanitize your half-pint or smaller jars, and wash and prepare your lids. Do not boil the lids (unless you are using reusable lids, then follow manufacturer instructions).

Puree the soaked chiles in a blender or food processor until smooth, using just enough of the reserved soaking liquid to make them easy to blend. Work in batches if necessary.

Pour this into a large non-reactive pot over medium-low heat.

Peel the tomatoes and roasted onions and unwrap the roasted garlic cloves from their foil packet.

Puree these in batches as well, using the rest of the reserved chile liquid to thin the mixture enough to blend easily.

Pour the roasted vegetable puree into the pureed chile and spice mixture and stir again.

Add the salt, lime juice, oregano, and cumin to the pot of salsa roja, and bring the salsa mixture up to a boil.

Stir frequently to prevent scorching. Adjust salt, pepper, and cumin to taste. You can also add more lime if you like, but do not use less than the specified amount.

Using a canning funnel (if possible) fill the jars with the hot salsa mixture, leaving ½” headspace. Work quickly and keep mixture hot while filling jars.

Using a thin non-metallic spatula, thin wooden spoon, or jar tool, remove air bubbles from the jars and adjust headspace as needed.

Wipe jar rims. I use a paper towel or clean lint-free towel dipped in hot water, followed with a clean towel dampened with distilled vinegar. Clean jar rims make good seals!

Place your prepared lids on the jars and secure with rings (check rings for dents and discard any damaged rings).

Using jar tongs or a canning jar rack, transfer the hot jars into the boiling water canner and make sure there is at least an inch of water over the jars with room to boil. Top up from a hot kettle of water if needed.

Process in your boiling water bath for 25 minutes (increase as needed for elevations above 1000 ft). Make sure the water is boiling hard the whole time. Do not start the processing timer until the pot is boiling vigorously.

When the time is up, turn off the burner under the pot, wait 5 minutes, and then carefully remove the jars with jar tongs (or remove the jar rack, if you used one).

Place the jars on a towel-covered or wooden surface or wire rack and leave undisturbed until completely cool. If it’s cold or drafty, you may want to cover the jars with a towel so they cool evenly. Do not tighten the bands (unless you are using reusable lids: if so, follow manufacturer instructions).