Step 1

Combine oil, garlic and sage in a glass or ceramic dish. Add lamb and turn to coat. Cover and refrigerate for 1 hour.

Step 2

Preheat oven to 180°C. Spray a large frying pan with oil. Heat over medium-high heat. Cook lamb for 5 minutes, turning, or until lightly browned. Remove to a wire rack in a large roasting dish. Roast for 20 minutes for medium or until cooked to your liking.

Step 3

Meanwhile, make leek, potato and mustard salad: Cook potatoes in a saucepan of boiling water over medium-high heat for 10 minutes or until tender. Drain. Allow to cool.

Step 4

Heat 1 tablespoon oil in a frying pan over medium-low heat. Add leek. Cook for 5 minutes or until tender.

Step 5

Whisk remaining oil, vinegar and mustard in a large bowl. Add potatoes, leek and chives. Toss gently to combine (see note). Divide salad between plates. Top with lamb. Serve.