20 lbs paste tomatoes (romas, oxhearts, pastes)
citric acid powder (also known as sour salt)
Start by washing all your tomatoes and sterilizing your jars in boiling water for 10 minutes. Once your hot water is done sterilizing your jars, you can use it to dip your tomatoes to get the skins off. Working in batches, dip your tomatoes into boiling water for 20-30 seconds. Then put them into a sink filled with cold water and ice to stop the cooking process. Once all the tomatoes have been dunked, start peeling them.
When all the tomatoes have been skinned, take about 1/4 of them (I take the ugly ones) and chop them. Put them in a pot large enough to hold all the tomatoes. Bring to a simmer. Cut the rest of the tomatoes in half and add them to the pot. While the tomatoes come to a simmer, prepare the pressure canner per the manufacturer’s instructions, and heat the lids in simmering water. I like to follow a reputable source when canning, since botulism is a real safety threat. I reference the USDA’s canning guide every time, just in case. Into each quart jar I add 1/2tsp salt and 1/2tsp citric acid (I don’t care for the “real” lemon bottled stuff.)
Load up the jars with hot tomatoes (who doesn’t love a hot tomato???), wipe the rims and screw on the lids. Put the jars in the pressure canner, adjust the lids and pray. Just kidding. I’d never used one of these pressure canner contraptions before, so it was a tinsy bit scary. I followed the instructions, letting the air out through the vent for 10 minutes, then put the pressure cap on. The gage climbed to 11 (yes, audiophiles, it does go to 11), then I adjusted the heat so it stayed there. I processed the tomatoes for 25 minutes at that pressure, then turned off the heat and let it depressurize on it’s own. Resist the urge to take the vent cap off–you’ve heard of the bends, right? If the canner depressurizes to quickly, your jars will loose liquid (or break) and it might affect the seal. You don’t want to go through all this work, only to loose a jar.