Teriyaki Steak Recipe

Make sauce base

In a small bowl or measuring cup, combine 1/2 cup low-sodium soy sauce, 2 tbsp mirin, 1 tbsp sake, 2 tbsp dark brown sugar, 1 tsp granulated sugar, 1 tsp grated fresh ginger and 1 minced garlic clove. Whisk until sugars dissolve and mixture is uniform.

Thicken and finish

In a separate small bowl, stir 1 tsp cornstarch into 1 tbsp cold water to make a slurry. Heat the soy-mirin mixture in a small saucepan over medium heat until it just begins to simmer. Whisk in the cornstarch slurry and simmer gently for 1–2 minutes until the sauce slightly thickens and coats the back of a spoon. Remove from heat and stir in 1/2 tsp toasted sesame oil. Let cool to room temperature before using as a marinade. If using immediately as a glaze, keep warm on the lowest heat and stir occasionally.

Optional finishing add-ins

If desired, stir 1/2 tsp furikake or additional toasted sesame seeds into a small portion of the sauce reserved for finishing.

Pat the 6 oz flap steak dry with paper towel. Lightly score the surface in a crosshatch (optional) so marinade penetrates better. Season both sides with 1/2 tsp kosher salt and 1/4 tsp freshly ground black pepper. Brush or rub 1 tsp neutral oil evenly over the steak to help heat transfer during grilling.

Place the steak in a shallow nonreactive dish or resealable plastic bag. Pour 3/4 of the cooled teriyaki sauce over the steak (reserve approximately 1/4 of the sauce for finishing). Make sure the steak is coated, press out excess air if using a bag, and refrigerate to marinate for 30 minutes to 2 hours. (Longer than 2 hours can begin to cure the surface because of the soy/sugars.)

Preheat your grill (kiawe/mesquite or charcoal preferred for that smoky flavor) to high heat, aiming for 500–600°F (260–315°C) surface temperature. If using a gas grill, preheat to high. Oil the grate lightly right before grilling.

Remove steak from marinade and let excess drip off. Pat lightly if there is excessive sauce; reserve the marinade left in the dish/bag for potential brushing (do not reuse raw marinade as a finished glaze unless you boil it first).

Grill the steak over direct high heat: for a 6 oz flap steak about 1/2–3/4 inch thick, grill 2–3 minutes per side for medium-rare (internal temp 125–130°F / 52–54°C). If thicker, adjust time: 3–4 minutes per side for medium (135°F). Avoid flipping more than once. During the last 30–60 seconds per side, brush the reserved, boiled (or previously cooked) portion of the teriyaki sauce onto both sides to create a glossy glaze.

Optional smoky finish: if using kiawe/mesquite, allow short flare-ups for char but manage to avoid burning the sugar in the glaze; move to cooler zone if charring too quickly.

Remove steak from the grill and transfer to a cutting board. Tent loosely with foil and rest for 5–7 minutes to allow juices to redistribute.

Slice the steak thinly against the grain into bite-size strips. Arrange on plate and drizzle any remaining warmed teriyaki glaze over the slices (do not use raw marinade).

Sprinkle 1 tbsp thinly sliced green onion and 1/2 tsp toasted sesame seeds over the sliced steak. Serve with a lemon or lime wedge on the side if desired for a squeeze of brightness.

Serve immediately while hot. Leftover cooked teriyaki steak can be refrigerated up to 3 days; reheat gently to avoid overcooking.