Trim the sirloin steak of any silver skin (the thin, translucent connective tissue that doesn't break down when cooking), then cut into 1-inch cubes. Place the cubed steak in a bowl or resealable bag, making sure all pieces are in a single layer so the marinade can coat them evenly.

In a separate bowl, combine the soy sauce, water, sesame oil, honey, worcestershire sauce, minced garlic, and grated ginger. Whisk together until the honey dissolves completely and all ingredients are well combined. Add the rice vinegar and ground black pepper, stirring to incorporate. I always use Kikkoman soy sauce because it has a balanced saltiness that doesn't overpower the other flavors, and I find that freshly grated ginger gives a much brighter, more vibrant taste compared to pre-minced versions.

Pour the teriyaki marinade from Step 2 over the cubed steak from Step 1, ensuring all pieces are submerged. Cover the bowl or seal the bag, then refrigerate for at least 30 minutes up to 6 hours—longer marinating time will deepen the flavor and tenderize the meat more effectively.

Remove the steak from the marinade, allowing excess marinade to drip back into the bowl (reserve the marinade). Heat a large skillet or wok over medium-high to high heat until very hot. Working in batches if needed to avoid overcrowding, sear the steak cubes for 2-3 minutes per side until they develop a golden-brown crust. I find that letting the steak sit undisturbed for the first minute allows a better crust to form—don't stir it around too much. Once all pieces are seared, pour the reserved marinade into the skillet and simmer for 1-2 minutes, allowing the sauce to glaze the meat and reduce slightly.

Transfer the seared steak and its sauce to a serving dish or individual plates. Allow the meat to rest for 5 minutes before serving—this helps the juices redistribute throughout the meat, keeping it tender and moist rather than losing all those flavorful juices when you eat it.