Place the cubed sweet potatoes in a large pot and add enough water to cover the potatoes. Season the water with the salt and bring to a boil. Reduce the heat and simmer the sweet potatoes until tender, about 10 minutes.

While the potatoes are cooking, chop the fresh parsley. Set aside.

Drain the potatoes well and then return to the pot.

Mash the cooked sweet potatoes with a fork to your desired consistency.

Add the chopped parsley, garlic, cubed butter, and sour cream to the mashed potatoes and season with a pinch of black pepper and salt. Mix well.

Transfer the mashed potatoes to a serving bowl sprinkle with some more parsley and drizzle the top with the olive oil. Serve warm.