Ingredients:

  • 1 lb flank steak (450 g), trimmed and sliced thinly against the grain into 1/4-inch (6 mm) strips
  • 1 tbsp soy sauce (15 ml)
  • 1 tsp cornstarch (5 ml)
  • 1 tsp vegetable oil (5 ml)
  • pinch of coarse black pepper (about 1/4 tsp / 1 g)
  • 1 medium red bell pepper (about 150 g), seeded and cut into 1/2-inch (12 mm) strips
  • 1 medium green bell pepper (about 150 g), seeded and cut into 1/2-inch (12 mm) strips
  • 1 medium yellow or white onion (about 150 g), cut into 1/2-inch (12 mm) wedges
  • 2 garlic cloves, minced (about 8 g)
  • 1 tsp fresh ginger, minced (5 g)
  • 3 tbsp low-sodium soy sauce (45 ml)
  • 1 tbsp oyster sauce (15 ml) or 1 tbsp hoisin (optional)
  • 1/2 cup beef broth or low-sodium chicken broth (120 ml)
  • 1 tbsp rice vinegar (15 ml)
  • 2 tsp granulated sugar (8 g)
  • 1/2 tsp freshly ground black pepper (about 1 g)
  • 1 tsp sesame oil (5 ml)
  • 1 tbsp cornstarch (8 g)
  • 2 tbsp cold water (30 ml)
  • 2 tbsp vegetable oil or neutral oil (30 ml), divided
  • 2 scallions, thinly sliced (optional garnish)
  • 1 tsp toasted sesame seeds (optional garnish)

Instructions:

  1. Slice steak thinly across the grain into 1/4-inch strips. Toss with 1 tbsp soy sauce, 1 tsp cornstarch, 1 tsp vegetable oil and a pinch of coarse black pepper. Let sit 15 minutes (optional) or proceed immediately.
  2. Whisk together 3 tbsp low-sodium soy sauce, 1 tbsp oyster sauce (or hoisin), 1/2 cup broth, 1 tbsp rice vinegar, 2 tsp sugar, 1/2 tsp black pepper and 1 tsp sesame oil in a small bowl to make the sauce.
  3. Mix 1 tbsp cornstarch with 2 tbsp cold water until smooth to form the slurry; set aside.
  4. Heat a large wok or heavy 12-inch skillet over high heat until very hot. Add 1 tbsp vegetable oil and swirl to coat.
  5. Sear the beef in batches: add half the beef so pieces lay flat and do not overcrowd. Cook about 1–2 minutes without moving until browned, toss and cook another 30–60 seconds until mostly cooked but still slightly pink. Remove to a plate and repeat with remaining beef.
  6. Add remaining 1 tbsp oil to the pan and sauté minced garlic and ginger 15–30 seconds until fragrant. Add onion wedges and bell pepper strips and stir-fry 2–3 minutes until crisp-tender and bright.
  7. Return beef and any accumulated juices to the pan. Pour in the prepared sauce and stir to combine. Bring to a simmer.
  8. Gradually stir in the cornstarch slurry until the sauce thickens and becomes glossy, about 30–60 seconds. Taste and adjust seasoning with more soy, vinegar or sugar as needed.
  9. Remove from heat. Garnish with sliced scallions and toasted sesame seeds if desired. Serve immediately over steamed rice or noodles.