1) Get a very large pot of water boiling to sterilize cans and to process the jars after filled.
2) Add jars to pot and bring to a simmer. Let simmer for 5-10 minutes while you make the salsa.
3) Sterilize your jar lids and bands and all your tools in a small pot of boiling water as well. Keep the lids and bands in the boiling water until you are ready to use them to make sure they stay really clean.
4) To make salsa, shuck corn and place under a broiler on high heat for about 3 minutes per side. Turn and continue to broil until corn is nicely charred. You can also grill the corn to get a nice char on it.
5) Dice tomatoes, peppers, and onion and add to a large pot.
6) Toast cumin, coriander, and red pepper flakes over medium heat in a dry skillet. Once toasted and fragrant, grind spices. You can also just use ground spices.
7) Once corn is charred, let cool until you can handle it, then slice the corn off the cob and add to pot with tomatoes and peppers. Add spices to pot along with vinegar, sugar, lime juice, and salt.
8) Bring salsa to a simmer and simmer for about 10 minutes until it starts to reduce and thicken. Taste and adjust spices and seasoning to your liking.
9) Remove jars from water bath and sit on a clean towel. Divide salsa between jars and leave at least 1/2 inch of space at the top of each jar.
10) Wipe rims to ensure they are clean and add lids to jars and tighten bands around lids. Use a magnetic lifter to add the lids so they stay nice and clean.
11) Add filled and sealed jars to a boiling water bath and let process for 15 minutes.
12) Remove jars from pot and let cool for 24 hours. You should hear them “ping” and the center pressure button should be down. If you can press it down and it pops up then the jar isn’t sealed correctly and you shouldn’t store the jar although you can use it immediately.
13) Once the jars have cooled, you can remove the bands and store for a year in a cool, dry place. Open jars should be used within two weeks.
For more info on canning, the book Food in Jars is excellent.