For the marinade: Place a large bowl on a digital scale and set scale to zero. Measure 20 grams of yuzu kosho. Set scale back to zero and measure 10 grams rice vinegar. Set scale back to zero again and measure 70 grams of oil. Whisk to combine and set aside.
Season short ribs very lightly with salt and a tiny bit of pepper. Brush a little oil on the meat so it doesn't stick. Place on the grill and cook about 5-6 minutes, flipping and moving around often until they're "medium" done. When the meat is ready, place it directly into the marinade so that the juices mix with the seasonings. Toss so the meat is evenly coated in the marinade. Immediately serve on a plate family-style.