Tomato Conserva

Every week, a DIY expert spares us a trip to the grocery store and shows us how to make small batches of great foods at home.

In this edition of Small Batch, Marisa McClellan of Food In Jars shows us how to preserve the last of summer's tomatoes with tomato conserva. Marisa is the author of Food in Jars: Preserving in Small Batches Year Round.

Each year, when late summer rolls around, I throw a little one-woman tomato festival. I buy 100 pounds of tomatoes from one of my local farmers and spend a long weekend engaging in the act of putting up. The first 50 pounds are earmarked for canning whole. I typically get around 25 quarts of whole peeled tomatoes, which means that if I play my cards right, I’m set for soups, stews and sauces for an entire year.

The rest get turned into more specialty products. Tomato jam, a product that has entirely replaced ketchup in my household, takes five pounds. Ten pounds are halved and slow roasted for twelve hours, becoming this urban dweller’s version of sun-dried tomatoes. I marinate and dehydrate (ten pounds), make a few jars of pizza sauce (six pounds) and stir together two different kinds of salsa (18 pounds between the two).

Finally, when the kitchen is streaked red from one end to the other and I can’t bear to ever look at another tomato, I pull myself together, collect all the remaining tomatoes and make a batch of tomato conserva. It is essentially glorified tomato paste, but once you taste it, you’ll understand that it deserves every ounce of that glory.

I will warn you that in concept, it doesn’t actually sound like a good investment of time or resources. You chop and simmer the tomatoes until tender. They you work them through a food mill, sieve or chinois and spread the runny pulp out on rimmed cookie sheets. It cooks for hours in the oven, has to be stirred regularly and the yield is always ridiculously small. And yet, it’s not until the moment when the process is done and I have a few small jars of dense, intensely flavored tomato concentrate tucked into the freezer, that I can exhale and let the autumn come.

Having a several half pints of tomato conserva in the freezer is my way of holding onto the intense sunshine of summer and, when layered in a toasted cheese sandwich, it wards off my January blues better than any workout or Vitamin D pill can.

When making tomato conserva, the variety of tomato you choose can greatly impact the finished yield. I made it this year with heirloom tomatoes, because some farmer friends sold me massive amounts of split (but still very good) heirlooms for cheap. However, because they’re such watery tomatoes, ten pounds of tomatoes yielded just one and a quarter pints. If you choose to start with a meatier tomato, like a roma, plum or paste, you’ll end up with more. My best advice is to choose tomatoes that taste good to you, because this product intensely concentrates the tomato flavor.

Tomato conserva
Makes about 2 1/2 cups

10 pounds tomatoes
1/4 cup olive oil (plus more for topping)
2 teaspoons sea salt

Chop tomatoes into quarters. Combine them in a large pan with 1/4 cup olive oil and bring to a simmer. Cook until they are soft and the peels begin to detach from the tomato flesh.

Push warm tomatoes through a food mill, sieve or chinois, so that you separate the tomato pulp from the seeds and skins.

Divide the tomato pulp between two large, rimmed baking sheets (I used two half sheet pans).

Place baking sheets in the oven and bake at 350° F. Check tomatoes every half hour, stirring the paste and switching the position of the baking sheets so that they reduce evenly.

Over time, the conserva will start to reduce to the point where it doesn’t fill the baking sheet any more. At this point, I combine the contents of the two pans into and continue to bake.

When the conserva is shiny, brick-colored and has reduced by more than half, it is done. There shouldn’t be any remaining water or moisture separating from the paste at this point.

Scrape finished conserva into clean half or quarter pint jars. Top with a layer of olive oil and place in either the refrigerator or the freezer. As long as you keep it well-covered with olive oil and ensure that you only use a very clean spoon to remove it from the jar, it will keep in the fridge for a month or so. Frozen, it will keep for up to nine months.

Save and print the recipe here.

Marisa will be answering questions about tomato conserva on the Hotline for those of you who want to take on this project at home. For the quickest response, go to her recipe and ask a question from there -- we'll email her your question right away!

In next week's Small Batch, Phoebe Lapine leads the way to better hummus with homemade tahini.