Don't be fooled by the short list of simple, easy ingredients. This soup tastes surprisingly complex, considering. It's got all the hallmarks of classic, comforting tomato soup - bright flavor, gorgeous crimson hue - along with the smoky addition of roasted red peppers. Perfection.
In a large saucepan over medium heat, bring the tomatoes, butter, and diced onion to a boil. Reduce heat to low and simmer uncovered for about 45 minutes, until the tomatoes begin to break down and droplets of butter float free from the tomatoes. If using whole tomatoes, break them up with a spoon as they cook.
Add the vegetable broth and garlic, then return to a simmer. Simmer for another 10 minutes.
Stir in roasted red peppers.
Remove from heat. Let mixture cool to room temperature so that it’s safe to puree without danger of burning yourself.
Puree ingredients in a blender, food processor, or right in the pan with an immersion blender. Return the mixture to the pan and return to a simmer over low heat.
Stir in half-and-half and add salt and pepper to taste. Return to a simmer, then serve.