Step 1: Prepare the tomatoes by blanching them in boiling water for 30-60 seconds until skins crack, then immediately dipping them into an ice bath. Peel, core, and chop the tomatoes, placing them in a large stainless steel pot.
Step 2: Add the diced onions, bell peppers, jalapeños, and minced garlic to the pot with the tomatoes.
Step 3: Stir in the lime juice (or vinegar), salt, cumin, and sugar. The acid is crucial for safe canning.
Step 4: Bring the mixture to a boil over medium-high heat, stirring frequently to prevent scorching.
Step 5: Reduce heat and simmer for 20-30 minutes until the salsa reaches your desired consistency. Stir in the fresh cilantro during the last 5 minutes of cooking.
Step 6: While the salsa simmers, sterilize your pint jars and lids in boiling water.
Step 7: Ladle the hot salsa into the warm jars, leaving 1/2 inch of headspace at the top.
Step 8: Remove air bubbles by sliding a non-metallic spatula around the inside of the jar. Wipe the rims clean with a damp cloth.
Step 9: Center the lids on the jars and screw on the bands until finger-tight.
Step 10: Process the jars in a boiling water bath canner for 15 minutes (adjusting for altitude if necessary).
Step 11: Remove jars from the canner and place them on a towel-lined surface. Let them sit undisturbed for 24 hours before checking the seals.