Place bread in a blender. Pulse 10 times or until coarse crumbs form. Place breadcrumbs in a large bowl.
Combine bell pepper and next 5 ingredients (through garlic). Place half of bell pepper mixture and 1 cup broth in blender, and process until smooth. Add pureed bell pepper mixture to breadcrumbs; stir well. Repeat procedure with remaining bell pepper mixture and remaining 2/3 cup broth. Stir in vinegar, sugar, Sriracha, and salt. Spoon 1 1/4 cups soup into each of 4 bowls, and drizzle each serving with 1/2 teaspoon oil.