Pan-roasted pink ling with sweet potato chips & avocado yoghurt

Ingredients

• 1/2 avocado
• 1/2 cup Greek yoghurt
• Juice of 1/2 a lemon
• 1/4 tsp honey
• 1 tbsp finely chopped chives
• 2 medium sweet potatoes
• 2 tbsp olive oil
• 4 thick pink ling fillets (about 150g each), or other firm white fish
• salt and pepper
• dill sprigs and lemon wedges, to serve