1. Preheat the oven to 200°C/fan 180°C/gas 6.
2. Cut the potatoes into thin wedges.
3. Mix together 2 tbsp olive oil with the chilli powder, ground ginger and ground coriander. Add the potatoes and toss gently. Season with coarse salt and tip on to a non-stick baking sheet.
4. Roast the potatoes, shaking now and again for 25 – 35 minutes or until the wedges are soft and golden brown.
5. Mix together half the lime juice, sweet chilli sauce and chilli flakes.
6. Halve the avocados and remove the stones. Scoop out the avocado flesh and mash with the remaining lime juice and oil. Keep the avocado skins for serving the dip.
7. Add the lime juice and chilli mix and mash lightly. Stir the coriander leaves through the mix. Spoon the mixture into the avocado skins.