In a large stock pot, heat oil over medium heat. Add onion and garlic, cooking until onion begins to soften. Add ginger and continue warming until fragrant.
Pour in stock, orange (or apple) juice, carrots, thyme and corriander. Bring to a boil. Cover and cook until carrots are very soft - about 15 minutes.
Remove from heat. Using an imersion blender (or transfer in batches to a blender), blend until smooth and uniform texture.
Return to low heat. Stir in buttermilk. Season with hot sauce and pepper. Do not let soup boil. Stir until heated through.
Ladel into serving bowls and sprinkle with additional thyme or corriander. (Pictured: added are oyster crackers for garnish)
No buttermilk in your fridge? Make your own by adding 1 tsp of lemon juice to 1/2 c of skim or 1% milk, stir and let stand for 5-10 minutes.