Nostalgia for this glorious summer is moments away. Schools are opening, bright red sumac lines the highways, the cool, crisp mornings signal autumn’s approach. If there is only one project you undertake this summer, this should be the one. Tomatoes will soon be gone, and you will regret missing the opportunity to stash some away for the winter.

I’m not going to try to convince you that this is a quick, tidy process. It’s messy and hot. But it’s also ridiculously easy, and the benefits are huge. Besides, it’s fun.

Other than a few jars, no special equipment is needed: just a couple of big pots. The critical part of the process is properly and safely acidifying the tomato mixture. To guarantee a pH of around 4.6, add lemon juice or, my favorite, citric acid. For every quart you’ll need two tablespoons of lemon juice, or about two small lemons. Citric acid, used at ½ teaspoon per quart, is a much more economical option. Citric acid is widely available at grocery and hardware stores.

Start with one box of tomatoes: 25 pounds of big, round, sturdy field-grown tomatoes. Leave the yellows, purples, greens and other heirlooms for sandwiches and pies; they can be a little tender for this process. Roma, or Italian plum tomatoes, for canning purposes, are better suited for a purée, passed through a food mill to remove the sturdy skin and seeds.

To keep costs down, ask at the market for “seconds” — imperfect but still worthy — and make sure to cut away any black spots. Above all, avoid mushy or overripe tomatoes: When crushed or sauced, they have a thin and disappointing taste. The best canned tomatoes start out bright, firm and just barely ripe.

Buckle down and crush the entire box of tomatoes. That will take a little over an hour, if working alone, but if you gather friends around you, it will take just a few minutes (so obviously you should crush two or three boxes). Blanch and peel and seed and crush. Twenty pounds’ worth of the 25 will be enough to put up seven quarts of bright, tasty, easy-to-use crushed tomatoes.

And with the eight cups of crushed tomatoes that remain? Make a zesty one-pot barbecue sauce, stir it lazily and then put that sauce in a jar, too. Think of it. In your pantry: a brick-red barbecue sauce with lashings of mustard and molasses, fresh and dried chiles, and a slightly smoky finish. That’s going to be useful.

But first, spend the afternoon with a box of tomatoes. You’ll thank me in February.


Cathy Barrow’s is the author of “Mrs. Wheelbarrow’s Practical Pantry: Recipes and Techniques for Year-Round Preserving,” to be published in November.