• Process the onion, garlic, carrots and celery in a food processor until pureed.
• Alternatively, if you don't have a food processor, put the onion, garlic, carrots and celery in the jar of a blender, and add 1 1/2 cups of water. Process until the vegetables are very finely chopped. Strain this mixture using a fine strainer, then add the olive oil to the vegetable mixture.

Pressure Cooker Directions:

• Using the saute feature of an electric pressure cooker or on the stovetop if using a standard pressure cooker, saute the vegetable/olive oil mixture on medium-high heat for 15 minutes, stirring often. If using the Instant Pot or electric pressure cooker, adjust the heat of the saute setting to the second highest setting. Season with 1/2 teaspoon salt and 1/2 teaspoon black pepper during cooking.
• Add the crushed tomatoes, sugar or agave syrup, Italian seasoning, dried basil red pepper flakes and an additional 1 1/2 teaspoons salt, and stir to blend.
• Cook on high pressure for 20 minutes. For the Instant Pot, use the "Soup" setting but adjust the time down from 30 to 20 minutes.
• Allow the pressure to reduce using a natural pressure release, then remove the lid of the pressure cooker.

Crock-Pot Directions:

• Saute the vegetable/olive oil puree in a large skillet over medium high heat for about 15 minutes, stirring often. This step is optional, but it helps develop the flavor of the sauce. Season with 1/2 teaspoon salt and 1/2 teaspoon black pepper during cooking.
• Add the vegetable/olive oil mixture to the Crock-Pot, then add the crushed tomatoes, sugar or agave syrup, Italian seasoning, dried basil red pepper flakes and an additional 1 1/2 teaspoons salt, stirring to blend.
• Cook on high for 4 hours. Add a little water if the sauce is too thick.

Stovetop Directions:

• Saute the vegetable/olive oil puree in a large pot over medium high heat for about 15 minutes, stirring often. Season with 1/2 teaspoon salt and 1/2 teaspoon black pepper during cooking.
• Add the vegetable/olive oil mixture to the Crock-Pot, then add the crushed tomatoes, sugar or agave syrup, Italian seasoning, dried basil red pepper flakes and an additional 1 1/2 teaspoons salt, stirring to blend.
• Simmer the sauce, uncovered or partially covered, over medium to medium low heat for 1 hour. Add a little water if the sauce is too thick.