Peel and cut the sweet potatoes into 3/4-inch cubes.
Heat a 1 inch layer of oil in a fryer or a skillet. Once the oil is heated to 350°F, gently drop the sweet potatoes into the oil and fry them for 7 minutes, stirring occasionally. Fry them in batches, if necessary.
Remove the sweet potatoes from the oil once they are cooked through. Put them on a plate lined with paper towel to absorb any excess oil.
In a separate skillet, add 2 Tbsp oil, 2 Tbsp water, 1/2 cup sugar, 1/2 tsp cinnamon, and 1/4 tsp salt. Turn the heat on medium and stir until all the sugar is dissolved to make a syrup. Add the fried sweet potatoes to the syrup and gently toss them until evenly coated.