1) In a large pot, saute onion and garlic in olive oil on low heat. Cover with lid and let onions and garlic soften. Add celery and carrots and mix well, replace lid and saute for 5 minutes. Add potatoes and sweet potatoes,stock, sweetener, spices, and soy sauce. Stir well. Bring to a boil. Once potatoes are soft (can cut through them with a knife or about 10 minutes), remove from heat.
2) Let cool for 5 to 10 minutes. Scoop into blender or food processor and puree. Continue until all vegetable chunks have been used. You may have some leftover stock which you can add to thin the bisque or store for another soup. Season with pepper or vegan creme fraiche and enjoy!
Note: Sweet potatoes are loaded with vitamins and are an excellent source of anti-oxidants. They truly are a super food.
Source of recipe: I created this recipe.