Cut steak into smaller, equally-sized pieces that are easier to handle with tongs.

Meanwhile, in a medium bowl, combine cucumber, carrot, and 1 tablespoon salt. Add vinegar, water, remaining sugar and remaining scallions. Mix until combined and chill until ready to serve.

Preheat a grill (or grill pan) to medium-high. Once hot, remove the meat from the marinade and place on the grill. Season with pepper and grill the steak for about 3 minutes per side (depending on the thickness) for medium-rare. Transfer steak to cutting board, cover with foil and let rest for 5-10 minutes. Slice the steak against the grain into thin strips.

Divide rice, steak, and cucumber salad among four bowls. Sprinkle bowls with sesame seeds.