Peel and thinly slice the carrots, finely chop the onion, and peel and chop the garlic cloves.
In a large saucepan, heat oil over medium heat. Add carrots, onion, garlic and ginger and cook, stirring occasionally, until onion is golden, 6 to 8 minutes. Meanwhile, grate the orange to yield 2 teaspoons grated zest. Juice orange to yield 1/2 cup orange juice.
Add chicken stock, orange zest, and bay leaf to cooking vegetables. Bring to a boil. Reduce heat to medium-low, cover and cook, stirring occasionally, until carrots are tender, about 20 minutes.
In a food processor or blender, puree soup in batches until smooth; return to saucepan. Stir in orange juice and season with salt and pepper to taste.
Cook over medium heat, stirring occasionally, until heated through, 2 to 3 minutes. Mince parsley to yield 2 Tbsp. Garnish each soup bowl with a dollop of sour cream or yogurt and sprinkling of parsley.