Cut potatoes into bite-sized pieces and soak in water for 5 minutes. Peel daikon radish thickly, cut into quarters lengthwise, then slice into 2cm pieces. Trim edges for rounded corners. Cut carrot into irregular chunks and slice onion thinly.

Heat salad oil in a pot over medium heat. Add pork and stir-fry until the color changes. Add potatoes, daikon, carrot, and onion, and stir-fry for 3–4 minutes until coated with oil.

Add water and sake, bring to a boil, and skim off any foam. Add mirin and sugar, mix well, cover, and simmer on low heat for 7–8 minutes.