- Toss strips of beef in cornstarch and black pepper in a bowl to coat.
- Heat ½ inch of neutral cooking oil in a deep frying pan over medium heat for 3-4 minutes, until very hot. Test a strip of beef to ensure oil is hot enough by lowering into oil with tongs. If beef starts to sizzle and fry, the oil is ready. Working in two batches, add strips of beef and cook for 3-4 minutes until beef is crispy and golden brown, turning once for even frying. Transfer cooked beef to a bowl.
- Discard oil and clean pan. Whisk together ingredients for sauce and pour into pan over medium-low heat. Simmer sauce for 1-2 minutes, until thickened. Add broccoli florets to pan and cook 1-2 minutes. Add beef back to pan and stir to coat.
- Serve over rice and garnish with green onion.