Dice the potatoes and sweet potatoes.
Soak the potatoes and sweet potatoes in cold water to remove the starch.
Heat cooking oil in a pan and stir-fry the potatoes and sweet potatoes.
Mix soy sauce, sugar, water, and minced garlic to make the seasoning sauce.
Add the sauce to the stir-fried potatoes and sweet potatoes and simmer.
Finish with sesame oil and sesame seeds.