LONDON BROIL MARINADE
4 garlic cloves, thinly sliced
1/4 cup extra-virgin olive oil
2 Tbsp. good-quality balsamic vinegar
2 Tbsp. soy sauce
1 Tbsp. Worcestershire sauce
Freshly ground black pepper
¾ tsp. baking soda
1½–2 lb. London broil
Whisk together 4 garlic cloves, thinly sliced, ¼ cup extra-virgin olive oil, 2 Tbsp. good-quality balsamic vinegar, 2 Tbsp. soy sauce, and 1 Tbsp. Worcestershire saucein a medium bowl or baking dish; season with freshly ground black pepper. Whisk in ¾ tsp. baking soda (don’t worry if marinade fizzes; that’s the baking soda Prick one 1½–2 lb. London broil all over with a fork and add to marinade; turn to coat. Let sit at room temperature at least 1 hour or cover and chill up to 12 hours.
Heat 1 Tbsp. vegetable oil in a large cast-iron skillet over medium. Remove steak from marinade, letting excess drip back into bowl, and pat dry with paper towels; reserve marinade. Season steak generously with kosher salt and cook, turning once, until deeply browned and an instant-read thermometer inserted into thickest part registers 125° for
medium-rare, 8–12 minutes. Using tongs, stand steak on its sides and cook until lightly browned, about 30 seconds per side. Transfer to a cutting board and let rest 10 Meanwhile, transfer reserved marinade to a small saucepan, add ⅓ cup water, and bring to a boil (mixture will foam up). Cook over medium-high heat, stirring constantly to avoid overflow, until foaming subsides, about 3 minutes. Add 2 Tbsp. unsalted butterand whisk vigorously to emulsify sauce. Keep warm until ready to serve.
