Cumin-crusted vegetables

INGREDIENTS

• 600g/1lb 5oz potatoes
• 1 tsp black mustard seeds
• 1 tsp cumin
• 2 tbsp sunflower oil
• 1 tsp garam masala
• ½ tsp turmeric
• 1 medium red onion
• 1 yellow pepper
• 1 red pepper
• 1 orange
• 2 medium courgettes
• freshly ground black pepper