1.Preheat the oven to 180°C fan-forced. Peel potatoes and cut each into 3-4 long, thick slices. Transfer slices to a saucepan, cover with cold water, add a few pinches of salt and bring to a gentle bubble. Cook gently for 5 minutes then drain.
2.Mix paprika, cumin, garlic, lemon zest, oil and salt together in a large bowl. Add drained potatoes while they are hot and toss carefully. Add red capsicum and onion and gently toss once more.
3.Transfer to a shallow roasting tin lined with baking paper, scraping in all the oily flavourings and spreading vegetables so they are mostly in a single layer.
4.Bake for 20 minutes, remove from oven and turn vegetables with tongs to encourage even browning. Cook for a further 25-30 minutes until golden. Serve hot.