Season the steak generously with salt and pepper. Let it rest while you gather the sauce components. Pro move: pat the surface dry first for a better sear.
Heat a skillet over medium-high heat. Add a touch of oil, then sear the steak to your preferred doneness. Rest the steak for a few minutes; those juices aren’t going to rediscover themselves.
In the same pan, lower the heat and add minced garlic. Sauté for about 30 seconds until fragrant—don’t burn it, we’re not roasting the garlic here.
Pour in balsamic vinegar, soy sauce, and honey. Stir in Dijon mustard if you’re using it. Scrape up any browned bits from the pan with a wooden spoon; those bits are flavor gold.
Simmer the sauce for 3–5 minutes until it thickens to a glossy glaze. If it’s too sharp, introduce a pinch more honey or a splash of water. If it’s not thick enough, give it a bit more simmer time.
Turn off the heat and swirl in the butter until it’s melted and the sauce looks velvety. Slice the steak against the grain and spoon the glaze over the top. Serve hot.
