3 tablespoons oyster sauce
3 tablespoons tamari
2 tablespoons rice vinegar
4 tablespoons vegetable oil, divided
1 pound brussels sprouts, halved
8 ounces flank or skirt steak, thinly sliced against the grain
4 scallions, whites chopped, greens sliced
3 garlic cloves, sliced
2 tablespoons chopped peeled ginger
1 tablespoon garlic chili sauce
Optional steamed rice (for serving)
1. Whisk oyster sauce, tamari, vinegar, garlic chili sauce, and 1/4 cup water in a small bowl; set sauce aside.
2. Heat 2 tablespoons oil in a large skillet over medium-high heat. Add brussels sprouts and cook, tossing occasionally, until golden brown, about 4 minutes. Cover and cook until crisp-tender, about 3 minutes longer. Transfer to a plate; wipe out skillet.
3. Season steak with salt. Heat 1 tablespoon oil in same skillet over high heat until just beginning to smoke. Add steak in a single layer; cook until browned, about 3 minutes. Turn and cook until nearly cooked through, about 30 seconds. Add to brussels sprouts.
4. Heat remaining 1 tablespoon oil in same skillet. Add scallion whites, garlic, and ginger and stir until fragrant, about 1 minute, adjusting heat as needed.