County Clare, my favorite Irish Pub in Milwaukee, makes a great Root Soup. My version is rich, but without the whipping cream their original recipe calls for, and with ingredients you may already have on hand.
Place sliced carrots in microwave safe container, add a splash of water, cover and microwave about 10 minutes.
Or use any cooked carrots.
The sweet potatoes can also be microwaved. Place on a plate and cover with a paper towel. Microwave until soft - they will smell great - about 8 minutes.
Or use leftover baked sweet potatoes. Feel free to add left over boiled or baked white potatoes too.
Saute onion in olive oil and butter in a large,heavy sauce pan until rich in color to develop flavor (just short of burning) add garlic near end of cooking, and pour in the six cups of chicken stock.
Add carrots and potatoes. Let everything simmer about 10 minutes and then use your immersion blender to create a puree. If you have a conventional blender,divide into batches and return puree to the same pan.
Salt and/or pepper to taste. Use white pepper if you are concerned about black specks in your beautiful orange soup. Let soup simmer 20 minutes or so.
Serve plain or add a dollop of sour cream to each serving. You might want to get fancy and apply sour cream (thinned with milk) with a squirt bottle to make designs on your soup. A sprinkle of parsley or pinch of herb de provence can top it all off.