Peel the potatoes and dice them into bite-sized cubes.

Heat cooking oil in a pot over medium heat and sauté the diced potatoes.

Add diced beef and 1 tbsp mirin to the pot, and continue sautéing.

Add enough water to cover the ingredients and bring to a boil.

Dice the vegetables (mushroom, zucchini, onion, tomato) into bite-sized pieces.

Add the diced vegetables to the pot and add more water if needed. Simmer until all ingredients are tender.

Mix in the curry powder and stir well to combine.

Add diced tomato and stir to incorporate.

Add more water if the curry is too thick, and stir in sliced green onion.