Prepare all ingredients by slicing beef, potatoes, and onion into bite-sized pieces.

Make dashi stock by boiling water with kombu (seaweed).

Heat a pan or wok with a small amount of oil and sauté the onion until slightly softened.

Add diced potatoes to the pan and continue sautéing.

Once the potatoes and onions are lightly browned, add the sliced beef and cook until browned.

Pour in 1 cup of dashi stock, soy sauce, sugar, and a pinch of black pepper.

Bring the mixture to a boil, then cover and simmer until the potatoes are tender and the liquid has reduced.