Preheat the oven to 400°F.
While the oven is preheating, get started on prepping your vegetables.
Cut the Roma tomatoes in half. Cut the bell peppers into 4 -5 long slices and the onion into quarters.
You will also need to cut the cremini mushrooms in half and separate the garlic cloves. Leave the garlic skin on. You can also leave the cherry tomatoes on the vine. We will discard the vine before pulsing the sauce.
Place them on the baking sheet as you can see in the picture above. Rub the veggies with a teaspoon of olive oil and a pinch of salt.
Bake the tomatoes, peppers, and aromatics for 25-30 minutes at 400F, or until charred.
Once done, take it out of the oven and let it cool down. You want to blend the sauce while it is still warm.