Be sure the onions and tomatoes are cut into evenly sized pieces. Add the tomatoes, garlic, and onion to a mixing bowl or food storage bag. Add the olive oil and, season with salt & pepper, and toss to coat.
Transfer to a sheet pan with a raised 1-inch lip and spread evenly over the pan.
Roast for 30 to 35 minutes or until soft. Drain any excessive liquid from the pan and set it aside.
Add the roasted vegetables to a blender or food processor and puree until it reaches desired consistency. If it's too thick add some of the reserved liquid or water to thin it out.
Mix in the chopped herbs, taste for seasoning, and add salt as needed before serving.
This recipe can easily be scaled to use as many tomatoes asyou have on hand.
To ensure even cooking, be sure the onions and tomatoes are cut into evenly sized pieces.
If you’re using cherry tomatoes or very small tomatoes, there is no need to cut them.
Seeding larger tomatoes will make a thicker sauce with a lot less water content.
If you want to get charring on your vegetables, be sure not to overcrowd the pan.
If there’s a lot of water in the pan, either drain it or use a slotted spoon to remove the vegetables from the pan. This will keep the sauce from getting watered down.
If you haven’t peeled your tomatoes, I recommend using a blender, as it does a better job of processing the skin into the sauce.
The color of the sauce will vary depending on the shade of your tomatoes.
For a richer sauce, add a tablespoon of tomato paste and cook for 10 to fifteen minutes.
To cut acidity, add a little sugar or baking soda at a time (tasting in between) until it reaches your desired flavor.