Core and slice tomatoes in half, then add them, cut side down, to a foil-lined pan. Add Fresno chiles (if using), and garlic bulb with the top sliced off. Spray veggies or drizzle with 1 tablespoon olive oil, then sprinkle with ¼ teaspoon salt and black pepper.
Roast vegetables in a preheated 425°F oven for 25 minutes. Broil for a few minutes if the tomatoes are still not charred. Once cool enough to handle, remove peel from the tomatoes, garlic, and Fresno chiles (discard chile seeds).
While the veggies roast, add diced onion and 2 tablespoons olive oil to a Dutch oven and sauté the onion for 20 minutes over low to medium heat until caramelized. Strain bottled roasted red peppers and add to the onions.
Add roasted veggies to the pot along with seasoning, herbs, brown sugar, and baking soda.
Measure rendered tomato juice from the pan and add enough water or broth to it to equal two cups. If using water, stir in chicken bouillon, then pour over the soup ingredients.
Mix ingredients to combine, then simmer over low heat for 10 minutes. Use an immersion blender to blend until smooth. Add balsamic vinegar, then taste and adjust seasoning as needed. For a creamier texture, stir in half-and-half or heavy cream (1 to 2 tablespoons per cup).
Notes
The nutritional values do not reflect the optional addition of heavy cream or half- and half.
Instead of drizzling on the oil, I prefer using this spray bottle to spray the veggies with oil because you'll use less oil.
After blending, run it through a fine mesh strainer or food mill for a restaurant-smooth finish. (Or leave it rustic and chunky—your call!)
Tomatoes can get sharp. Add a splash of cream to smooth out the edges.
Store leftover soup in an airtight container in the fridge for up to 5 days. Freeze for up to 4 months.
If freezing the soup, leave some headspace in the freezer bag for expansion, and don't add the cream until serving.