Rinse cubed potatoes in a colander under cold water to remove starch; shake well to remove excess water.
Heat oil in a frying pan over medium heat. Cook and stir dried chiles until puffed and beginning to blacken, about 4 minutes. Remove from pan. Increase heat to medium-high.
Place potatoes in the pan. Cook, stirring constantly, until translucent around the edges, about 5 minutes. Add onion whites and garlic; saute for 1 minute. Mix in water, soy sauce, corn syrup and sugar. Cover and bring to a boil. Reduce heat to medium-low. Cook, stirring frequently, until potatoes are tender and sauce is thickened, 7 to 10 minutes.
Remove potato saute from heat. Season with salt and pepper. Garnish with onion greens.
You can use sweet potatoes in place of yellow potatoes, if desired.