Preheat oven to 425 and grease a baking sheet with nonstick cooking spray.
Cut potatoes into 1/2 cubes.
In a mixing bowl, combine potatoes and 2 tablespoons vegetable oil. Mix well to evenly coat.
Spread onto prepared baking sheet in a single layer. Bake for 20-25 minutes, flipping once halfway through. When potatoes are baking, make sauce.
In a large skillet, add sugar, water, 1 tablespoon oil and soy sauce. Heat over medium heat, stirring constantly until boiling.
Once boiling, reduce heat to medium and continue to boil. The bubbles will be like fizz from a can of coke. Continue to boil for 4-6 minutes, stirring constantly until liquid is reduced in half. Remove from heat.
Stir in potatoes and serve topped with sesame seeds.