In a large saucepan over medium heat, heat olive oil. Add the onion and sauté until softened. Reduce the heat to medium-low and add the tomatoes, bell peppers, garlic, chile and stock. Cover partially and cook until the vegetables are softened. Remove from heat.For a smokey flavor, saute the red peppers separately until blackened on both sides.
In a blender, puree the vegetables in batches until smooth. Alternatively, process with a handheld blender in the pan until smooth. Pass the pureed soup through a medium-mesh sieve set over a serving bowl, pressing on the pulp.
Discard any solids left in the sieve. Season to taste with salt and pepper. If you serve it chilled, let cool to room temperature, cover and refrigerate the soup until it is well chilled. (4 hours minimum.) If served chilled add a dollop of sour cream or yogurt.
If served hot (recommended), chop up some basil, olives, and/or parsley for garnish and top with cheese -- mozz, ricotta and parm works best.