Cover the bottom of a large skillet with about 1/4″ of oil and heat over medium heat until oil is hot.
Scrub the sweet potato and dice into small 1/4″ cubes (do not peel).
Add the diced sweet potatoes and stir to coat in the oil. Fry about 5 minutes, stirring occasionally, until all the potatoes are cooked through and tender. Remove from heat and stir in scallions.
Season generously with salt and pepper, then serve topped with sour cream, or creme fraiche.