Step 1 Place potatoes in a medium heatproof or microwave-safe bowl with 1/4 cup water. Cover with two sheets of cling film and cook in microwave on high for 5–6 minutes, or until potatoes are just tender. Drain potatoes and leave to cool.
Step 2 Preheat a medium grill pan or barbecue hotplate. Spray chicken fillets lightly with olive oil; season with cracked black pepper. Cook chicken for 3–4 minutes per side, or until golden and just cooked through. Remove pan from heat, cover and set aside.
Step 3 Meanwhile, cut cool potatoes into 0.5cm slices. Place slices in a large salad bowl with lemon juice, lemon zest, olive oil and capers; toss to combine. Add baby kale (or baby rocket) leaves, green beans and parsley to bowl. Slice reserved chicken and add to bowl; toss to combine.
Step 4 Divide salad among serving plates, season with cracked black pepper and serve.