Agri-Food Week | Transformation | Tomato Sauce

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

The transformation or processing stage of the food system can have many different steps and types of transformation, including food preservation. Food preservation is saving food for later, like turning strawberries into jam, or tomatoes into tomato sauce! 

Whenever you are canning, be sure to consult reputable resources to keep canned goods safe.  It is important to add lemon juice to this canned tomato sauce to be sure the sauce is the proper PH for safe canning.” 
This tomato sauce is a great "all purpose" sauce and a wonderful way to enjoy summer tomatoes all year round. 



Yield: 3 liters                           Level: intermediate



  • 10 pounds roma, or other paste type tomatoes, blanched and skins removed, roughly diced
  • 2 large onions, diced
  • 4 cloves garlic, minced
  • ¼ cup olive oil
  • 1 bay leaf
  • 2 tablespoons sugar
  • ¼ cup fresh oregano, chopped (or substitute dried)
  • ¼ cup fresh basil, chopped (or substitute dried)
  • Salt to taste
  • Lemon juice (2 tablespoons for every 1L, need to figure out yield first)


  • Large pot
  • Cutting board
  • Chef’s knife
  • Paring knife
  • Measuring cups
  • Measuring spoons
  • Slotted spoon
  • Bowls, various sizes
  • Wooden spoon
  • Blender or immersion blender
  • Tasting spoons
  • Dish towel


  • Mason jars, fresh sealing lids, and rings
  • Canning tongs
  • Stock pot 
  • Funnel
  • Ladle


Get Organized!

Gather all your ingredients and equipment before you get started! 


Get Prepped!

To prepare the tomatoes,  fill a large pot with water and bring to a boil. Remove the stem of the tomato and gently score the bottom of the tomato with an “X”.  Set up a large bowl of water and add a generous amount of ice.  In batches, carefully drop the tomatoes into the water, 5-6 at a time for about 30 seconds.  Scoop out of the tomatoes with a slotted spoon, and transfer to the ice water until cold.  Repeat this process for all of the tomatoes, and then take out of the ice water; the skins should easily slip off. If the skins are difficult to remove, repeat the process. Roughly dice the tomatoes.

Cut the onions in half and remove the skin.  Slice off the end and then from tip to root, make incisions almost all the way to the root, leaving the root end intact.  Turn the onion to dice it.  

Smash the garlic with the side of the blade of a chef’s knife and remove the root end.  Mince the garlic finely.  

If using fresh herbs, remove them from the stem and then chop the basil and oregano, and discard the stems.  

Measure the olive oil, sugar, and bay leaf.


Get Cooking! 

Over medium heat, sweat the diced onions in the olive oil for 5-10 minutes, until they are translucent.  Add the garlic and continue to cook one more minute.  

Add the diced tomatoes, sugar, bay leaf, chopped herbs, and season with pepper and salt.  

Cook for about 60 minutes over low heat, until tomatoes are broken down very well and sauce is slightly thickened. 

Using an immersion blender or a regular blender in batches,  blend the sauce to your desired consistency.  Taste for seasoning, and transfer back to the pot.  Continue to cook 15-20 more minutes until sauce is thick and delicious.  

If canning sauce, transfer sauce to clean sterilized mason jars and pack while hot.  Add 2 tablespoons of lemon juice to every 1 liter jar of sauce and stir with a clean spoon.  Add the sterilized mason jar lid and can according to reputable sources canning instructions.   

Alternately, sauce can be cooled and frozen and thawed at a later time when needed, lemon juice does not need to be added.  



  The Clark Family Foundation
Urban Harvest Landscape
zdybThe Wilson Family FoundationThe Joanne and Tom Cowan Fund
The William and Katharine Kostuk Family FundLove Alchemy Cornerstone
TillsonburgLFHSGoodlife Fitness