Method

• 1.
  Place potatoes in a large saucepan with reserved whey from ricotta and a good pinch of salt. Add enough extra water to cover the potatoes if needed. Place the pan over high heat and bring to the boil. Reduce heat and simmer for 30-35 minutes until potatoes are cooked. Drain and cool slightly.
• 2.
  Preheat oven to 90°C. Meanwhile, for the celery salt, spread celery leaves on a heatproof wire rack set over a baking tray and bake for 30-35 minutes until dried but still green. Set aside to cool, then crumble into a bowl and stir through celery seed and salt flakes. (Celery salt can be stored in an airtight container for up to 4 weeks.)
• 3.
  Increase oven to 220°C. Transfer potatoes to a large roasting pan, add half of the celery salt and a good drizzle of olive oil, and toss well to combine. Roast, tossing frequently, for 40-45 minutes until golden and crisp. Transfer to a platter, scatter with remaining celery salt and serve warm or cold.