Cut the Wagyu beef into 1 cm cubes and lightly salt and pepper. Cut the onion into 3cm squares.
2
Heat the cooking oil in a saucepan, add the beef, lightly cook until brown, and remove from the saucepan. Sauté the onions in the same saucepan and return the beef.
3
Add the water, bring to a boil, then simmer on low heat for 20 minutes while skimming off the scum.
4
Add A and the mixed beans and simmer further for 6 minutes on medium heat. Continue boiling on high heat for a short time to reduce some of the liqud.
