Caribbean fish stew

Ingredients

• 2 tablespoons vegetable oil
• 1 medium onion, diced
• 1 teaspoon ground cumin
• 1 clove garlic, crushed
• 80g frozen pepper, thawed, or ½ fresh red pepper, sliced
• 320g new potatoes, halved
• 1 green chilli, deseeded and finely chopped (optional)
• 200ml fish stock
• 600ml water
• Freshly ground black pepper
• 4 x 140g fillets white fish, fresh or frozen, skinless
• 80g frozen peas
• 80g frozen sweetcorn, or ½ x 198g can salt-free sweetcorn
• 3 tablespoons low-fat natural yoghurt
• Handful fresh coriander, chopped (optional)