As with all canning recipes, this recipe has been developed and tested specifically to make sure the pH level is safe for canning. Don't alter the amount of acidity (vinegar). You CAN substitute some of the vinegar for bottled lemon juice if you want to play around with flavor. Dried spices won't affect pH, so you can also experiment with those, but the amount of vegetables and tomatoes and acidity need to stay the same. I have not canned this recipe in a pressure canner, but I have given details in the post above about steam canners vs. water bath canners. Please do your own research to decide what method is best for you.
Katie, a 35 minute processing time is TOO long for salsa- the reason your canned tomatoes need that long is because you don’t add a cup of vinegar. Do a quick Google search to find that all the reputable salsa recipes call for 15 minute processing time (extension services, and the Ball Blue Book are two)- even for the recipes that have tomato paste added. I know you said it will make you feel better to go longer, but there are good reasons not to: energy costs and over-cooking the salsa are two good ones.
Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil over high heat, then carefully lower the jars into the pot using a holder. Leave a 2 inch space between the jars. Pour in more boiling water if necessary until the water level is at least 1 inch above the tops of the jars. Bring the water to a full boil, cover the pot, and cook for 30 more minutes.
Sterilize the jars and lids in boiling water for at least 5 minutes. Pack the salsa into the hot, sterilized jars, filling the jars to within 1/4 inch of the top. Run a knife or a thin spatula around the insides of the jars after they have been filled to remove any air bubbles. Wipe the rims of the jars with a moist paper towel to remove any food residue. Top with lids, and screw on rings.
I just made this wonderful salsa a couple of days ago with roma tomatoes. I 4X the recipe and ended up with 32 pints of salsa. We liked it so very much I am thinking of doing more with the 1 1/2 bushels of regular tomatoes that I have. Do you think that the regular tomatoes would have too much liquid in them or would the draining take care of that problem? I didn’t add the paste last time so I would probably add it for sure to make it thicker.