Slow-Cooker Low-FODMAP Marinara Sauce Recipe

slow cooker marinara sauce
Patsy Catsos, MS, RDN, LD
Total Time: 330 min
Prep Time: 30 min
Cook Time: 300 min
Servings: 6 (1/2 cup each)

Nutrition Highlights (per serving)

80 calories
5g fat
9g carbs
2g protein
Show Nutrition Label Hide Nutrition Label
Nutrition Facts
Servings: 6 (1/2 cup each)
Amount per serving  
Calories 80
% Daily Value*
Total Fat 5g 6%
Saturated Fat 1g 5%
Cholesterol 0mg 0%
Sodium 420mg 18%
Total Carbohydrate 9g 3%
Dietary Fiber 3g 11%
Total Sugars 6g  
Includes 0g Added Sugars 0%
Protein 2g  
Vitamin D 0mcg 0%
Calcium 35mg 3%
Iron 1mg 6%
Potassium 531mg 11%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calorie a day is used for general nutrition advice.

If you are lucky enough to acquire a few pounds of late summer tomatoes, you can make a fine batch of low-FODMAP marinara sauce in your slow cooker.

In this recipe, you will learn how to blanch tomatoes. Although very thin, tomato skins do call unwanted attention to themselves when they haven't been removed from marinara sauce. Blanching will make the skins slide right off the tomatoes, and improve the texture of your sauce a great deal.


  • 2½ pounds whole fresh ripe tomatoes
  • 1 medium carrot, chopped
  • 1 large celery stalk, chopped
  • 2 tablespoons garlic-infused olive oil
  • 1 teaspoon salt
  • 2 tablespoons tomato paste
  • ¼ - ½ teaspoon crushed red pepper flakes (optional)
  • 1 tablespoon Italian seasoning


  1. In a large pot, bring about 6 quarts of water to a rolling boil over high heat. Using a large slotted spoon, slip several tomatoes into the boiling water. After 60 seconds, remove them to a baking tray to cool, and blanch the rest of the tomatoes a few at a time.

  2. When they are cool enough to handle, use a paring knife or your fingers to slip the skins off the tomatoes. Cut them into large pieces and use your fingers to scoop out most of the seeds. Don’t worry if you don’t get them all.

  3. Put the tomatoes in a 3-quart slow cooker. Add the carrot, celery, oil, salt, tomato paste, pepper flakes, and Italian seasoning. Cover the slow cooker, and cook on high for 1 hour. Uncover, reduce heat to low, and cook, stirring occasionally until the carrots are tender and the sauce has reduced to the desired thickness, about 5 hours. Cooking time and yield will vary depending on the variety of tomatoes used, whether you have seeded them, and your slow cooker. If your slow cooker won’t maintain a low enough simmer with the cover off, try propping the cover open with a wooden spoon.

  4. Cool the sauce to a safe handling temperature, then purée it if desired. Submerge a stick blender into the slow cooker vessel or purée it in batches in the bowl of a blender.

Ingredient Variations and Substitutions

Keep a batch of garlic-infused oil in the freezer to quickly and conveniently add garlic flavor to recipes; FODMAPs do not migrate into the oil, so the oil can be used on the elimination phase of a low-FODMAP diet. To make just a little for this recipe, heat 1 clove of coarsely chopped garlic with 2 tablespoons plus 1 teaspoon of olive oil in a small skillet or saucepan over medium heat until the garlic begins to brown. Discard the garlic or reserve it for another use.

Substitute 2 teaspoons dried oregano, ½ teaspoon crushed rosemary, and ½ teaspoon dried thyme leaves for the Italian seasoning.

Cooking and Serving Tips

Removing the seeds is optional. Although we don't mind a few seeds in our tomato sauce, the gel that surrounds the seeds is full of water; removing them helps the sauce cook down much faster.

The marinara sauce freezes well, so it can be enjoyed over several meals. And, it doubles easily for a 4-quart slow cooker.

So-called “paste” tomatoes are ideal for making the sauce, as they are meatier than other varieties, and have a higher yield. Your local farmer’s market is probably the best place to purchase these.

If you don’t mind bits of tomato peel and seeds in your sauce, or if you have a high-speed blender which can pulverize them, you can skip the blanching, peeling, and seeding step. Unseeded tomatoes might take several more hours to reduce to the desired thickness because there is a lot of moisture in the gel around the seeds.

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