2 x 300 g (10 oz) packs ready-prepared sweet potato wedges
1/4 teaspoon dried chilli flakes
salt and pepper
200 ml (7 fl oz) natural Greek yogurt
4 tablespoons chopped mint
1/4 cucumber, finely diced
Place all the spices in a small, heavy-based frying pan and cook over a high heat for 1 minute, swirling the pan to toast the seeds evenly. Transfer to a mortar and grind with a pestle until finely ground. Mix the ground spices with the oil, then toss with the sweet potato wedges in a large bowl.
Spread the wedges out in a large roasting tin, season with salt and pepper and scatter with the chilli flakes. Place in a preheated oven, 200°C (400°F), Gas Mark 6, for 20 minutes until beginning to brown. Meanwhile, mix together the ingredients for the raita and place in a small serving bowl.
Remove the roasted sweet potato wedges from the oven and serve with the raita for dipping.