Honestly the easiest soup you will ever make, roast off your sweet potato if possable as it will increase a depth of flavour an sweetness but if you can’t do that, simmer it peeled and cut up into cubes, drain, set aside the water for use in something else at a later date.. mash the sweet potato.. measure it out, add equal amount of a white bone broth to it, a pinch of salt, a pinch of pepper, a bit of nutmeg or all spice, a walnut size pat of butter and heat it though, serve as is or with a dollop of sour cream or yogurt or a swirl of heavy cream.
You could blend it if you wanted it really smooth but its good as it is with just the well mashed sweet potato..
Just another Day on the Farm 
for mom I make mine a little differently – I start with garlic, onions, and curry in olive oil, add chicken stock and cubed sweet potato. Once cooked, I put it through the blender. I like the idea of the yogurt or sour cream to top. I will have to try that next time.
Mmm, nom, NOM!
We eat sweet potato stew around here a lot. peeled and chopped up sweet potatoes, chicken thighs, corn, diced tomatoes, chicken stock, cumin, bay, salt &pepper. I make it in a crock pot when I’m going to be gone all day or very busy. Some times I add celery or other veggies depending on what is on hand. I like that the sweet potatoes don’t go completely to mush. I think I will give your soup a try. I love sweet potatoes.