Pat the sirloin steak dry with paper towels and cut it into 1-inch bite-sized cubes.

In a medium bowl, whisk together minced garlic, soy sauce, honey, rice vinegar, sesame oil, and optional red pepper flakes until the honey dissolves.

Add the cubed steak to the marinade, toss to coat, and let it sit for two minutes while you heat your pan.

Heat olive or vegetable oil in a large skillet over medium-high heat until shimmering, then add steak bites in a single layer without overcrowding the pan.

Cook for 2-3 minutes per side, turning to achieve an even sear and caramelization.

After the steak is cooked, continue cooking any pan liquid for another minute or two, stirring until the sauce thickens and coats the steak.

Transfer to a platter, then garnish generously with sesame seeds and sliced green onions before serving.