Step 1: Prepare your canning equipment. Wash 6 pint jars and lids in hot soapy water. Keep jars warm in a pot of simmering water until ready to use.
Step 2: Blanch the tomatoes in boiling water for 60 seconds, then shock in ice water to easily remove the skins. Core and chop the tomatoes.
Step 3: In a large non-reactive stockpot, combine the chopped tomatoes, onions, all peppers, garlic, vinegar, salt, cumin, and cilantro.
Step 4: Bring the mixture to a boil over medium-high heat, stirring frequently to prevent sticking.
Step 5: Reduce heat and simmer for 15-20 minutes until the salsa reaches your desired consistency. Remember that it will thicken slightly as it cools.
Step 6: Ladle the hot salsa into the prepared warm jars, leaving 1/2 inch of headspace at the top.
Step 7: Wipe the jar rims with a clean, damp cloth to remove any residue. Center the lids on the jars and screw the bands on until fingertip tight.
Step 8: Place jars in a boiling water canner, ensuring they are covered by at least 1-2 inches of water. Process for 15 minutes (adjust for altitude).
Step 9: Remove the canner lid, wait 5 minutes, then remove the jars and place them on a towel-lined surface. Let them sit undisturbed for 24 hours.
Step 10: Check seals by pressing the center of the lid; it should not pop back. Store in a cool, dark place.