Beef and black bean

Ingredients

• 1 tablespoon peanut oil
• 250 gram beef rump steak, sliced thinly
• 1 brown onion, cut into wedges
• 1 yellow capsicum (150g), chopped coarsely
• 400 gram choy sum, stems and leaves separated, chopped coarsely
• 1 1/2 tablespoon spicy black bean sauce
• 2 teaspoon japanese soy sauce
• 227 gram can whole water chestnuts, rinsed, drained, quartered
• 1 tablespoon water
• 2 tablespoon coarsely chopped roasted macadamia nuts