Rinse tomatoes and peppers. Core tomatoes and score a small "X" in the blossom end. Place tomatoes and peppers on hot grill and close lid. Turn frequently until peppers are charred and blistered and pretty much black all over. Tomatoes should have some blackened spots and blistered enough to remove the skins. Remove from grill. Place peppers in a bowl and cover with plastic wrap to steam for several minutes. Let tomatoes cool a bit on a cutting board until you can handle.
Update: Because I was paranoid about the peppers, I actually could have upped them a smidge. OTOH, right now it has a gentle heat which won't burn you out after a couple bites. I did lie though. I omitted the celantro because I am one of those whose tastebuds interpret it as soap. Something tastes like it needs a little more of something, but possibly I mis-measured because the taste is wonderful..I might not whirl the tomatoes quite as much next time though. Boy, this a long comment to basically say Brava.
A food processor makes chopping easier and less time consuming. Seed and cut the peppers into chunks, weigh them, then pulse the peppers into smaller pieces in the food processor. Add the chopped peppers to your saucepan. Chop your onions into pieces, weigh them, pulse in the food processor, and add to your saucepan. Skin your tomatoes, cut into smaller pieces, weigh them, pulse in the food processor, and add to your saucepan.
Combine ingredients in a large saucepan. Bring to a boil, then reduce heat and simmer, stirring frequently until thick (about 1 hour). Ladle hot mixture into pint jars, leaving 1/2-inch headspace. Adjust lids and process in boiling-water canner for 15 minutes at 0–1,000 feet elevation, 20 minutes at 1,001–6,000 feet, and 25 minutes above 6,000 feet.
Absolutely love this. You were right. Getting as much water out is so really important step. I drained as best I could with colanders then put in glass bowl. More liquid settled so I used a turkey baster to remove more liquid. Won’t ever make it another way. I have been looking for a salsa that has body and flavor and this is outstanding. I made my own tomato sauce as the tomatoes I got from local farmer were meaty and very flavorful. Thank you for posting this outstanding salsa recipe.