Peel and chop sweet potatoes into chunks, then boil in salted water for about 15-20 minutes until fork-tender. Drain and mash until smooth.

In a bowl, combine all-purpose flour, chopped onion, beaten egg, and spices to the mashed potatoes. Stir gently until just combined.

Scoop out portions and shape into patties about 2 inches wide and ½ inch thick. Rest the patties on parchment paper.

Heat olive oil in a skillet over medium heat. Once shimmering, cook patties for about 4-5 minutes on each side until golden brown.

Transfer cakes to a paper towel-lined plate to absorb excess oil. Serve warm with sour cream or Greek yogurt.