Fill water bath canner at least half-full with water. Cover and maintain a simmer (180°F) until jars are filled and placed in the canner.

Check jars, lids, and bands for proper functioning. Jars with nicks, cracks, uneven rims or sharp edges may prevent sealing or cause jar breakage. The underside of lids should not have scratches or uneven or incomplete sealing compound as this may prevent sealing. Bands should fit on jars. Wash all in hot, soapy water and dry well.

Preheat your canning jars in hot (180°F) water or run them through a quick, heated dishwasher cycle and leave them in there until ready to use. Keeping jars hot prevents them from breaking when filled with hot food and immersed in the canner. Leave lids and bands at room temperature for easy handling.

Preheat broiler to high and set rack about 4 inches from heating element. Lined a rimmed baking sheet with aluminum foil or parchment paper for easier cleaning. Working in batches, put the tomatoes cut side down on the baking sheet and broil for about 10 minutes, until the skin is blistered and black in places. Put the tomatoes in a large bowl and set aside. Broil the chiles, garlic, and onions until blackened. When the tomatoes are cool enough to handle, pull off the skins. You can discard them at this point, but I like to puree them separately from the vegetables and add some, or all, of the blackened peel into the salsa. This gives it the charred look, which I like! Put all the tomatoes in the bowl of a food processor and pulse until just coarsely chopped. The tomatoes are soft and only take 3 or 4 quick pulses. Then pulse remaining vegetables in food processor. As each batch is complete, transfer contents into a large stockpot. Once all the vegetables are in the stockpot, add the vinegar, salt, and sugar. Bring to a boil, turn down to medium heat and cook for 5 minutes.  Remove from heat.

Ladle the hot salsa into the jars, leaving 1/2 inch of space at the top of the can. Use a damp towel and wipe the rim of the jars. Then put a flat lid and ring on each jar and tighten until just finger-tight. Place the jars in the canning pot, making sure the water covers the top of the jars by at least 1 inch. Bring to a boil and boil for 20 minutes to process. Remove the jars to a folded towel and do not disturb for 12 hours. After 1 hour, make sure that the lids have sealed by pressing down on the center of each — if it can be pushed down, it hasn’t sealed and the jar should be refrigerated immediately. Label the sealed jars and store.