On a small sheet tray arrange the tomatoes, onion, peppers and garlic. Season with salt and pepper and broil for 15 minutes, or until they have developed a char and are cooked about halfway.
Carefully remove all the ingredients from the sheet tray, place in a small saucepan with the vegetable stock and heat on medium-high heat. Allow to come to a boil, reduce to simmer and cook for an additional 10 minutes. Using an immersion blender puree the contents of the pot to your desired consistency. Serve immediately.