Posted By Julie on August 20, 2010
One of my goals for this summer has been total use: making use every part of every food we buy, within reason. I prefer to think of it this way as opposed to simply reducing waste, although of course it is both. I’ve been doing pretty well at this so far—for instance, I detailed how I now break down my chicken here and my use of potato peelings here—and will be sharing more of my total-use tips in August alongside the Preserve the Bounty challenge. This week’s big project was making homemade tomato paste and lacto-fermented ketchup with farmer’s market produce, now that tomatoes are finally starting to show up.
I started with approximately 6.5 pounds of ripe tomatoes from Hermiston, Oregon. After hauling them home, the first order of business was to break them down. I don’t have a food mill (my aunt lent me one to play with a year or two back, but I wasn’t working in bulk then and returned it), so this process was a little bit onerous. It was in my best interest to peel the tomatoes first, so I X’d, blanched and chilled them, as with the peaches from a week ago but less problematic—it always seems like half my peaches peel easily and the rest fight me.
Next, I cut the tomatoes in half and seeded them as well as possible, then dumped them into the blender in several batches. By the time this was done, I had about 5 pounds of liquidy tomato puree, meaning that 1.5 pounds of skin and seeds were sloughed off. (More on that below.) Since we are currently having a heat wave, I decided to cook down my puree partly on the stovetop before transferring it to the oven, keeping it at a simmer and stirring periodically until most of the liquid had boiled off and only the solids remained. These were spread out in a non-stick cake pan with the convection oven set to about 250F, and cooked until very thick and dark. I ended up with just over a cup of rich tomato paste.
While the tomato paste was still boiling down on the stovetop, I took advantage of the empty oven to dehydrate the tomato skins. This is a perfect example of my effort to use every part of the food, making a richly flavored tomato powder from something that would ordinarily go straight in the trash. Laid out in a single layer on a silpat, the skins dried rapidly in my convection oven, transforming into a bowlful of what looked a lot like tissue paper—but not for long. I blitzed them up in batches in my spice grinder, and they were soon reduced to bright red powder. I don’t know precisely what I will do with this, but my first instinct is to add some to biscuits or bread dough for tomato color and flavor without the moisture. A fun, and not entirely anticipated, side effect of making tomato paste!
Finally, I decided to save the seeds from my tomatoes. I’ve been keeping an eye out for vegetables with harvestable seeds, thinking I might attempt to save and plant them next spring. So far I’ve got cantaloupe, black Hungarian pepper, and these. The process for drying tomato seeds is a little odd, requiring you to allow them to ferment (covered in plastic wrap with a pinhole for air) for several days before rinsing and drying. Apparently this helps to remove the gel coating from around the seeds and to eliminate some of the diseases they can harbor. Once my seeds looked appropriately “scummy,” I rinsed them thoroughly and dehydrated them in the oven until dry to the touch; they will sit in an open container for a week or so to ensure that all residual moisture is gone.
And after all that, what happened to the tomato paste? I used the majority of it to make lacto-fermented ketchup, and froze the remainder in a few small scoops for enriching future recipes. I won’t know how the ketchup comes out for a few days, as it needs to ferment for the lactic acid twang that replaces vinegar in the recipe and allows it to be stored for an extended period of time. It would have to be the best ketchup in the world to make up for the expense, effort and time involved, though, so I probably won’t make this again unless I have tomatoes coming out my ears—a possibility, I suppose, given the number of seeds I harvested.