Place Onion, Carrot, Celery, and Garlic in a Food Processor and pulse until it’s finely chopped. You want it to be almost a paste.
Add Olive Oil to a medium saucepan over medium heat.
Add vegetables, reduce to medium low, and sauté for about 5 minutes for them to soften. You don’t want it them to brown.
Add Tomatoes to the pan, along with any herbs, salt and pepper and Parmesan Cheese rind (if using) and give it a stir.
Add water to the empty tomato container, swish it around to get the rest of the tomatoes and add it to the pot.
Once the mixture comes to a boil, cover the pot leaving the lid slightly ajar. This prevents splatters and lets the sauce thicken some cook down some.
Reduce heat to low, and simmer for around 25-30 minutes, stirring occasionally.
Serve over your favorite gluten free pasta.