Cut bell peppers in half lengthwise; discard seeds and membranes. Place pepper halves, skin sides up, on a foil-lined baking sheet; flatten with hand. Broil for 15 minutes or until blackened. Place in a zip-top plastic bag; seal. Let stand for 15 minutes. Peel and chop.
Place peppercorns, thyme, and bay leaf on a double layer of cheesecloth. Gather edges of cheesecloth together; tie securely.
Heat oil in a large Dutch oven over medium heat. Add onion and garlic; cook 15 minutes or until onion is lightly browned, stirring occasionally. Add bell peppers, cheesecloth bag, broth, vinegar, and hot pepper sauce to pan. Increase heat to medium-high, and bring to a boil. Cover, reduce heat, and simmer 20 minutes. Remove and discard cheesecloth bag; stir in salt and black pepper. Place half of bell pepper mixture in a blender. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to prevent splatters). Blend until smooth. Pour pureed mixture into a large bowl; repeat procedure with remaining soup. Sprinkle with chives.