1. Heat a Dutch oven over medium heat. Coat pan with cooking spray. Add onion; cook 8 minutes or until tender, stirring frequently. Add garlic and thyme; cook 2 minutes, stirring frequently. Add stock; simmer 20 minutes. Remove and discard thyme sprig. Place half of stock 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 avoid splatters). Blend until smooth. Pour into a large bowl. Repeat procedure with remaining stock mixture.
2. Return stock mixture to pan; add pepper and potatoes, stirring with a whisk until combined. Bring to a simmer; cook 5 minutes. Remove from heat; stir in yogurt and dill. Ladle into serving bowls; top with green onions, cheese, and crumbled bacon.