Cooking Fresh

Tomato Sauce the Slow (and Cool-Kitchen) Way

By | July 01, 2011
Share to printerest Share to fb Share to twitter Share to mail Share to print
fresh red and yellow tomatoes

A common summer scenario involves an avid gardener or farmers’ market shopper loading bushels of seasonal tomatoes into a huge pot on the stove and making the sauce that will later become soup, or chili or spaghetti sauce.

Tomatoes have natural sugars in them that, like all sugar, burn at a relatively low temperature. That’s why you’re punished with burned chicken if you slather barbecue sauce on too early in the grilling process. And why tomato sauces tend to leave black spots in your pan when you simmer them on the stove.

I have a long history of carbonized food, especially when making my seasonal tomato sauce in pans that are cheap, thin and unequal to the task of anything but boiling water. I walk away, get distracted from stirring and the burning begins.

Years ago, a friend told me how she avoided not only burned sauce, but hours of simmering a hot pot on a hot stove in a hot kitchen in a hot season. There’s not enough air-conditioning in the world that can cool off a kitchen in tomato-sauce season.

She used her slow cooker. Pile tomatoes in a slow cooker (which she set on her covered porch to keep its heat out of the kitchen), remove the top, flip off the lights and go to bed. In the morning, you have tomato sauce. She popped hers in the blender, seeds and all. For some reason, I still put mine through a food mill, which is somewhat more laborious and I have no real explanation for why I do it that way.

Frozen by the quart (yogurt containers), this plain, unseasoned sauce gets pulled out all winter long for chili and spaghetti sauce that I make by formula: one quart of sauce, one pound of meat (Italian sausage or hamburger), one onion. The chili formula is the same but it gets a pound of dried red beans (and different spices). The sauce goes into soups, and gets poured over chuck roast for a slow oven simmer.

This slow, overnight method of tomato sauce making has held me in good stead (and kept my kitchen cooler) over the years as I have shopped farmers’ markets (I am no gardener). Ask them in advance, and farmers are glad to bring you their “seconds” by the bushel and sell them at a reduced price.

Last year, however, my slow-cooker method was really put to the test. I became a little obsessed with a new produce auction just up the road in Henry County, where 20-pound boxes of “seconds” could be had, on occasion, for $6 and never more than $9. At auctions, prices are unpredictable. If crowds are low and product abounds, the prices can be very low. But even on days of competitive bidding, buying a lot for a little is easy.

Driving 40 miles to get “a deal” on tomatoes probably isn’t practical. But it’s an outing for me like yard sale shopping or going to the mall is an outing for others. It’s fun to be in a warehouse full of Kentucky-grown food, and auctions are a little bit adrenalin-producing.

Slow-Cooker Tomato Sauce
Basic Spaghetti Sauce


Slow-cooker sauce is the most efficient way I’ve found to reduce a 20-pound box (or three) of tomatoes into sauce that’ll last the winter.

Here’s how I do it:

  • Core the tomatoes and remove any white or black spots with a paring knife (and cut away anyplace that looks like it’s rotting). If the tomatoes are plums or Romas, don’t core them.
  • Pile tomatoes in a slow cooker turned on high. I have mixed Romas and round, but Romas alone tend to burn because they have more solids and less juice, which is why they are preferred for sauce-making. I burned a batch once, and never went back to straight Romas again. If you do, you may need to add water and stir occasionally, and check them after 6 or 8 hours to see how the sauce is proceeding. They certainly won’t take as long to cook into sauce as round tomatoes.
  • Keep piling until the slow cooker can’t hold any more, until the last tomato you put on rolls off the top. Walk away.
  • After 12 or 20 or 24 hours, you can blend this mixture to make it smooth, or run it through a food mill. A blender blends in all the seeds and peel, but these are infinitesimal; a food mill removes skin and seeds. If the sauce seems too thin (a total judgment call), put the sauce back in the slow cooker and continue to simmer until it’s the texture you prefer. Freeze the sauce, or can it if you lack freezer space.

If you, like me, tend to overbuy or overgrow and have more tomatoes than will fit in your slow cooker, you can

  • Borrow another slow cooker
  • Buy another slow cooker
  • Start your sauce on the stove

Due to my carbonizing tendencies, the stove makes me nervous. However, when the tomatoes have a high water content (at the beginning of cooking), they are less likely to burn. So a large pot on a low burner can begin to soften the tomatoes and reduce a little of their liquid, moving them along in the process.

You should stir a few times. When your batch of tomatoes in the slow-cooker finishes, you can fill it with the contents of the pot.


Serves 4 to 6 as sauce for spaghetti noodles or ravioli.


  • 1 pound (local) ground beef or Italian sausage
  • 2 tablespoons olive oil, optional
  • 1 cup chopped onion, about 1 medium
  • 4 to 6 large cloves garlic, minced
  • 1 quart tomato sauce (see recipe above) (or 28 ounces canned crushed tomatoes)
  • 1 teaspoon dry basil
  • 1 teaspoon dry oregano
  • 1 teaspoon salt
  • ½ teaspoon black pepper
  • ½ teaspoon crushed red pepper


  1. Cook the meat in a wide, heavy pot (deep skillet or Dutch oven) over medium heat until it has lost its red color, stirring and breaking it up as it cooks. Drain and set aside. (If you like, drain it using a sieve and catch the fat in the pan — many times there won’t be much, but you can use what there is for cooking).
  2. Add enough oil to the pan to make about 2 tablespoons. Add onion to the pan and cook on medium heat about 15 minutes, stirring occasionally. Add garlic and cook 10 minutes more, stirring occasionally.
  3. Add tomato sauce, herbs, salt and peppers to the pan. Bring to a boil, then reduce heat to simmer. How long depends on how thick you like your sauce and how thick your tomato sauce was to begin with, but about a half an hour.
  4. Sauce freezes well.

The Capstone Produce Auction starts at 11 am Monday, Wednesday and Friday until Oct. 7 and can last for a couple of hours. After Oct. 7 the days and hours decline with the season.

To get there from Louisville:

  • Take I-71 North to exit 34 (US 421) Bedford/Campbellsburg.
  • Turn right (south) on US 421 proceed 2.5 miles.
  • Turn left at KY 55. Market is on the right after about 500 feet.
Article from Edible Louisville & the Bluegrass at
Build your own subscription bundle.
Pick 3 regions for $60
We will never share your email address with anyone else. See our Privacy Policyhere.