Agri-Food Week | Transformation | Tomato Ketchup

Note: This recipe is a part of the 2021 Spring Agri-Education Experience with the Western Fair District

 The process of making ketchup is not hard, but can be tricky to master because it's such a familiar texture and flavour!

The main producers of ketchup that we see at the grocery store have huge machines at their factories that make sure their ketchup is the perfect consistency every time. It can be difficult to master this at home, but it's a great opportunity to experiment and have fun! Ketchup is not runny or too stiff and has the perfect "gloopy" consistency that is a mix between a liquid and a solid. This is called a non-Newtonian fluid.  Other examples of non-Newtonian fluids are shampoo and toothpaste. 

Yield: 8 cups                                             Level: Intermediate


  • 1 teaspoon ground allspice
  • 4 bay leaves
  • 1 tablespoon ground cinnamon
  • 1 teaspoon celery salt
  • 1 teaspoon chili flakes
  • 3 ½ kilograms Roma or plum tomatoes, cored and concasseed
  • 2 tablespoons kosher salt
  • 2 cups apple cider vinegar
  • 1 ¼ cups light brown sugar
  • 4 yellow onions, peeled and diced
  • 4 garlic cloves, minced


  • Cutting board
  • Paring knife
  • Medium pot
  • Blender or food processor
  • Wooden spoon
  • Fine mesh strainer
  • Ladle
  • Rasp
  • Tongs


Get Organized!

Gather your mis en place; get together all of the equipment needed for the recipe and gather your ingredients.

Get Prepped!

Measure out the allspice, celery salt, bay leaves, chili flakes, cinnamon, sugar, salt, and vinegar.

Concasse the tomatoes. Bring a large pot of water to a boil and season with salt. Hold the tomato firmly on the cutting board and insert the knife next to the stem at a 45 degree angle. Spin the tomato around the knife to remove the core. Next, slice an “X” at the bottom of the tomato and repeat for all tomatoes. Submerge in the boiling water for 15-20 seconds, and remove and immediately submerge in the ice water, allow to cool completely. The skin of the tomato will peel away easily, then cut in half and roughly chop.

Using a rasp, mince the garlic into a bowl.

Chop the onion. Slice the onion in half from the root to the tip and peel off the outer skin. Then, place the flat side down on the cutting board and slice horizontally from the tip to the root, leaving the root intact to hold the slices together. Slice across the onion in the other direction to dice the onion.

Get Cooking!

Add all ingredients to the medium pot and place over medium heat. Cook, stirring occasionally, until the onion is translucent and the tomatoes are soft, about 30 minutes.

Transfer the sauce to the blender or food processor and puree.

Strain the sauce through a fine mesh strainer back into the pot.

Cook over medium low heat until thickened to your preference. Taste for seasoning and add salt as needed.

Ladle to a glass jar or squeeze bottle and store in the refrigerator for up to 3 weeks.



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