Preheat the oven to 425°.
Wash the tomatoes and put them onto a sheet tray. Take the garlic out of the head and put them on the sheet tray with the tomatoes. Coat everything in 2 tablespoons of olive oil, salt, and pepper.
Roast the sheet tray with tomatoes and garlic for about 30 minutes until the skins of the tomatoes begin to brown and look slightly charred.
While the tomatoes and garlic cook, heat a Dutch oven with 1 tablespoon of olive oil and add the chopped onions. Cook the onions for 15 minutes on medium heat until they are very soft and translucent. Turn off the heat until the tomatoes are done.
Turn the stove to medium and add the tomatoes and garlic to the Dutch oven with the onions. Add the vegetable broth, chopped basil, and dried oregano. Let that cook for 10 minutes to cook all the flavors together.
Next, we need to blend the soup. For this, I use an immersion blender. I like to leave a little bit of texture in the soup, but you can choose to blend it until smooth. You can also use a regular blender to blend the soup, just be careful not to overfill the blender with the hot soup as it can overflow. If you are using a blender, add only enough soup to fill the blender halfway, blend it and pour it into a bowl or a separate pot. Then continue doing that until the rest of the soup is completely smooth.
Once the soup is the consistency you are looking for, turn it back on the heat and let it simmer for another 10 minutes. This will really intensify the flavors. Taste the soup and add as much salt and pepper as you prefer. Serve immediately. This soup will keep in the refrigerator for about a week.