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Keto Sauces

Slow Cooker Tomato Sauce

There’s something special about a sauce that bubbles away all day, filling the kitchen with aromatic warmth. This slow cooker keto tomato sauce is my go-to for weeknight meals when I want deep, slow-simmered flavor without constant stirring. It's bright, slightly spicy, and perfectly low-carb, making it a versatile base for zucchini noodles or meatballs.

15 min Prep time 600 min Cook time 615 min Total time 8 Servings 105 Calories
Slow Cooker Tomato Sauce

Ingredients

  • roma tomatoes - peeled, seeded and crushed
  • /2 small onion, chopped
  • teaspoon minced garlic
  • /4 cup olive oil
  • teaspoon dried oregano
  • teaspoon dried basil
  • teaspoon ground cayenne pepper
  • teaspoon salt
  • teaspoon ground black pepper
  • pinch cinnamon

Instructions

  1. Step 1

    I start by peeling, seeding, and crushing the Roma tomatoes—a bit of work but worth the smooth texture. Then I toss them into the slow cooker along with the chopped onion, minced garlic, and a glug of olive oil. I sprinkle in all the dried herbs and spices: oregano, basil, cayenne, salt, pepper, and that tiny pinch of cinnamon which really rounds out the acidity. Give everything a gentle stir, pop the lid on, and set it to low. Now the magic happens over 10 to 15 hours of slow cooking

  2. Step 2

    the longer it goes, the deeper the flavor. At 10 hours, it’s already wonderful, but if you can wait the full 15, the sauce becomes incredibly rich and complex. I like to check and stir occasionally, if I’m around, but it’s mostly hands-off. Once done, use it immediately or let it cool for storage. It’s perfect over spiralized zucchini or as a pizza base.

Chef's Tip

A pinch of cinnamon might seem odd, but it cuts the acidity and adds a subtle warmth that enhances the tomatoes. I also recommend roasting the garlic beforehand for a mellower, sweeter note.

Storage Tips

Store leftover sauce in an airtight container in the fridge for up to a week, or freeze in portions for up to 3 months. Reheat gently on the stove, adding a splash of water if it thickens too much.

Variation Tips

For a meaty twist, brown some ground beef or Italian sausage and stir it in during the last hour. Or, swap the cayenne with smoked paprika for a milder, smoky flavor. Serve over grilled chicken or use as a dipping sauce for keto breadsticks.

Frequently Asked Questions