Preheat oven to 400F.
Toss tomatoes in oil to coat. Spread on a baking sheet in a single layer and roast for 25-30 minutes. Remove from oven when tomatoes have burst and are just starting to shrivel.
In large saucepan over medium-high heat, add 1/4 cup olive oil. Add onions and cook until tender, about 4-5 minutes.
Add the garlic and cook for another couple minutes until golden and fragrant.
Add the tomatoes to the saucepan, including all their juices, and the remaining ingredients.
Turn the heat down to low and let the sauce simmer for 10-15 minutes, stirring once or twice.
Remove sauce from heat and let it cool for 10-15 minutes. Carefully, transfer sauce into a blender and pulse until the desired consistency is reached.
Serve over hot pasta or use in any recipe that calls for tomato sauce. Store in an airtight container in the fridge for up to 1 week.