Pat the steak dry with paper towels. Into a sealable bag, add the soy sauce, vegetable oil, mirin, honey, garlic, scallions, sesame oil and Sambal (or other hot sauce). Add the steak, and move it around to ensure the surface is completely coated with marinade. Seal the bag and marinate for at least 1 hour at room temperature, though overnight (in the refrigerator) is best. If refrigerated, take steak out at least 30 minutes before grilling.
Preheat a grill or grill pan over high heat. Remove the meat from the marinade and pat steak dry with paper towels. Reserve the marinade. Brush steak lightly with a little oil to prevent sticking. Grill the steak to desired doneness, about 2 to 3 minutes per side for medium-rare, depending on thickness. Remove from heat when a thermometer reads 125 ℉ so the final temperature will be about 135℉. Transfer meat to carving board, cover loosely with foil and let rest for at least 10 minutes. Slice thinly against the grain.
To turn the marinade into a glaze, pour reserves marinade into a small saucepan and bring to simmer over medium-high heat. Simmer for at least 5 minutes to kill any bacteria. If a thicker glaze is desired, mix cornstarch with cold water until dissolved. While stirring, stream slurry into simmering liquid until thickened to desired viscosity.
To serve, sprinkle with sesame seeds and thinly sliced scallions and a drizzle of the glaze, if desired.