Step 1

Melt the butter in a large pot over medium-low heat. Add the onion and celery and cook until softened, about 10 minutes (don’t let them brown).

Step 2

While the onion and celery are cooking, pour the tomatoes along with the juice into a medium bowl and break them up using your hands (give them a good squish). Add the tomatoes and water to the onions and celery, and stir to combine

Step 3

Bring the mixture to a boil and then reduce the heat. Simmer the mixture for about 10 minutes or until it starts to thicken.

Step 4

Puree the mixture with a stick blender until smooth. If using a regular countertop blender, allow the puree to cool before blending.

Step 5

Store the puree in the freezer until ready to use. I divide mine into 1-cup portions before freezing.