Wrap the beef tightly in plastic wrap and place on a plate or small baking sheet. Freeze for 15 to 30 minutes, until the beef is partially frozen and firm to the touch.

Unwrap the meat. With a sharp chef ’s knife, slice the meat against the grain into strips that are 2 inches (5 cm) long, 1 inch (2.5 cm) wide, and ⅛ inch (3 mm) thick. The easiest and most efficient way to do this is to start by portioning the beef into pieces that are 2 inches (5 cm) wide and 1 inch (2.5 cm) thick, and then cutting those pieces crosswise into ⅛-inch-thick (3 mm) strips.

Put the strips of meat in a large bowl and drizzle the oil over them, then sprinkle with 2 tablespoons of the yaji. Carefully toss and massage the yaji into the beef until the meat is evenly coated. Season with another 2 tablespoons of the yaji.

Working with one piece of beef at a time, thread it onto a metal or wooden skewer, piercing each piece through twice to secure it, then spread the meat out on the skewer so it will cook evenly.

Leave 2 inches (5 cm) of the skewer exposed at either end. Place the completed skewer on a platter and repeat with the remaining beef. Once all skewers are assembled, sprinkle the remaining yaji on both sides. Cover and refrigerate the skewers for at least 30 minutes and up to 8 hours before grilling.

If using a charcoal grill, light a chimney starter full of charcoal. When the coals are hot and covered with gray ash, carefully spread them onto one side of the grill. If using a gas grill, set the burners on one side of the grill to high (leave the other side off ). Cover and preheat for 5 to 10 minutes. Clean and oil the grilling grate.

Place the skewers on the grill over direct heat and cook for about 8 minutes, turning them over once, until charred on both sides and cooked through. Transfer to a serving platter and let rest for 2 to 3 minutes before serving. (Alternatively, let the skewers rest for 1 to 2 hours, then reheat as needed.)

Serve the skewers with the yajin kuli, onion, and tomatoes.