Heat the oil in a large frying pan or wok. Add the vegetables and stir-fry for 3-4 minutes until they are nearly cooked. Add the prawns and ginger and fry for 1 minute.
Meanwhile, whisk sauce ingredients together in a bowl until smooth.
Add the sauce to the pan with the water chestnuts, bring to the boil, then stir until it has thickened and the prawns have turned pink. Season to taste, then serve with rice.
Broccoli is one seriously healthy vegetable. It’s one of the most concentrated sources of vitamin C, making it great for fighting infection, and is also a great source of calcium and vitamin K, crucial for bone health.