Preheat oven to 450 degrees Fahrenheit. Cut the fresh tomatoes in fourths or halves (depending on how big your tomato is) and lay on a sheet pan, sliced side up. Separate garlic cloves from the heads and add to the sheet pan. Rough chop onion and peppers and lay them on the sheet pan as well.
Drizzle olive oil over all the vegetables and toss to coat. Roast the vegetables in the oven until you see areas of browning. This can take up to a half hour, but watch closely. You don't want your veggies to dry out too much, but you want to see some nice roast marks forming.
Meanwhile, make a thickening roux by melting the butter in a large pot over medium heat. Add flour and stir until nice and incorporated, being careful not to burn the butter and flour mixture. Remove from heat.
To a blender, add your broth and herbs. When the vegetables are done roasting add them to the blender and blend all the ingredients until you get a smooth texture.
Add the contents from blender into your saucepan that has the roux, and stir. Let your soup simmer on medium-low heat without a lid until some of the moisture has dissipated and it is the thickness you desire.
Enjoy as is with garlic bread or a grilled cheese sandwich, or spruce it up with some mix ins!