Combine onions and oil in a microwave-safe bowl. Cover. Microwave on HIGH (100%) power for 3 minutes. Preheat barbecue grill and plate on medium-high.
Step 2
Cook onions on barbecue plate, stirring, for 5 minutes. Stir sugar into onions. Cook a further 3 minutes.
Step 3
Spray both sides of steaks with oil. Season. Cook on barbecue grill for 3 minutes each side. Remove to a plate.
Step 4
Spread rolls with hummus. Add spinach, tomatoes, beetroot, steaks, onions and bread tops. Serve.