Step 1Place potatoes in a steamer over a saucepan of simmering water. Cover them and steam for 12 minutes, or until tender, adding green beans for last 2–3 minutes of cooking time. Drain. Set aside to cool slightly.
Step 2Meanwhile, combine olives, lemon juice, parsley and olive oil in a bowl. Set mixture aside.
Step 3Combine flour, chilli flakes and zest in a large zip-lock bag. Add prawns, seal bag and toss to coat in flour mixture.
Step 4Heat remaining oil in a large non-stick frying pan over high heat. Cook prawns, stirring, for 2–3 minutes, or until golden and cooked through.
Step 5Combine watercress, potatoes, beans and half the olive mixture. Toss to combine. Divide salad between serving plates. Top with green prawns and drizzle with remaining olive mixture, and sprinkle with pine nuts.