Preheat the oven to 200 degrees celsius. Dice the potatoes into 3cm pieces, and place in a bowl. Add the peanut oil, soy sauce, garlic and pepper (to taste) to the potatoes, and toss well to combine.
Evenly spread the potatoes over a baking tray, and roast in the oven for 30-40 minutes or until the potatoes are tender and golden brown.
Before serving, garnish the potatoes with sesame seeds and spring onion.