If your beef isn't already sliced, slice it thinly against the grain. Aim for strips that are about 1/4-inch thick.

In a small bowl, whisk together the soy sauce, honey, rice vinegar, sesame oil, cornstarch, minced garlic, and minced ginger. Make sure the cornstarch is fully dissolved to avoid any lumps in your sauce.

Heat the vegetable oil in a large skillet or wok over medium-high heat. Once the oil is hot, add the beef and stir-fry it until it's browned on all sides. This should only take a few minutes. Don't overcrowd the pan; if necessary, cook the beef in batches.

Pour the sauce over the cooked beef in the skillet. Stir continuously until the sauce thickens and coats the beef evenly. This will happen pretty quickly, usually within a minute or two. You'll know it's ready when the sauce is glossy and has a slightly sticky consistency.

Remove the skillet from the heat. Sprinkle the sesame seeds and sliced green onions over the beef. Serve immediately over rice, noodles, or your choice of sides.