Heat oil in a large saucepan over medium heat. Add onion and carrot; sauté 5 minutes or until tender. Add tomato; cook for 10 minutes. Stir in pepper and broth; cook 10 minutes. Pour half of tomato mixture in blender; process until smooth. Pour soup into a large bowl. Repeat procedure with remaining tomato mixture. Ladle 1 cup soup into each of 6 serving bowls; top each serving with 1 tablespoon yogurt and 1/2 teaspoon tarragon.