Step 1

Preheat the oven to 400°F

Step 2

Spread out the tomatoes, onions, garlic, and peppers (if you’re using them) on sheet pans.

Step 3

Drizzle the tomatoes and other veggies with the olive oil and sprinkle with salt and pepper.

Step 4

Roast in the oven for 30-40 minutes.

Step 5

Let the tomatoes cool for a few minutes, then transfer the entire contents of the sheet pan, juices and all, to a blender or food processor. You may need to do this in two or more batches depending on how many tomatoes you have.

Step 6

Add the fresh herbs and balsamic vinegar to the blender if desired.

Step 7

Blend until the tomato sauce is smooth.

Step 8

Pour into jars and store in the refrigerator.