Trim the ends of the sweet potatoes, peel, and dice into 2-inch cubes. Place them in a medium pan, add salt and enough water to cover the potatoes, and bring to a boil. Reduce the heat to medium-low and leave to simmer for about 15 minutes. We want them soft but not mushy.
Drain all the water completely with a colander, return to the pot and mash the potatoes until they become smooth. A potato masher or ricer works best.
Add the butter, sour cream, minced garlic, salt, and pepper to taste. You can also add some milk to thin it out if necessary.
Serve hot.
Notes
For a bit of heat, add a splash of sriracha
Be careful with the garlic; a little goes a long way; otherwise, it will overwhelm the dish.