Pre heat the oven to 400 F.
Peel the carrots, onion and sweet potato. Dice roughly in chunky cubes. Layer these evenly on a cookie sheet and drizzle with the oil, salt and pepper. Roast in the middle rack of the oven for 30 minutes, tossing once in between.
Place a pot at medium high heat and pour the stock. If the stock is sodium-free, add 1 teaspoon of salt. Bring it to a boil and then, add all the roasted carrots, sweet potato and onion. Grate the ginger and add it the pot. Let it simmer for 10 minutes.
Using either a hand blender or a stand blender, blend it into a smooth consistency. Check for salt and add any, if needed.
Just before serving, add the garnish mentioned above or serve as is.