Add all of the simmering stock incredients into a big bowl and mix thoroughly. Set it aside.
Heat the vegetable oil in a stew pot or pan on medium high heat, and sear the beef slices.
When the color of the beef turns, add the onions. Stir fry for 2 minutes.
Add the potatoes and stir fry another 2 minutes.
Add the simmering stock, bring to a boil, then reduce heat to medium.
Cover and simmer, making sure to check on it for a quick mix it for even stewing every 5 minutes or so.
After 10 minutes, uncover the heat and crank up the heat to reduce the liquid down. When the consistency becomes less soup and more stewy, your dish is done.
Serve this with hot white rice and a side of miso soup. Short grain or sushi rice works the best.