- 1.
Heat your oven to 180°C/Fan 160°C/Gas 4. Scrub and slice the sweet potatoes as thinly as possible. Lay the slices in a medium sized baking dish.
- 2.
Heat a frying pan over a medium heat and tip in the peanuts. Toast for 3-4 mins till golden. Take care not to let them burn. Tip onto a chopping board and roughly chop.
- 3.
Finely chop the chilli, flicking out the seeds for a milder heat. Peel the ginger by scraping it with a teaspoon and roughly chop. Peel and roughly chop the garlic. Zest and juice the lime. Roughly chop the coriander stalks, saving the leaves for later.
- 4.
Tip the peanuts, chilli, ginger, garlic, coriander stalks, lime zest and half the juice into a food processor. Squeeze in the curry paste and pour in the coconut milk. Blitz to combine. Taste and season.
- 5.
Pour the fragrant coconutty sauce over the sweet potato. Tumble together with your hands, then spread out. Dot the tomatoes over the top.
- 6.
Cover the dish with foil and seal the edges tightly. Cook for 30 mins. Remove the foil and cook for a further 20 mins till golden. Check the sweet potatoes are cooked by piercing with a knife. If still firm, return to the oven and cook for another 5-10 mins.
- 7.
Whisk the remaining lime juice with 1 tbsp oil and some seasoning. Pour over the lamb’s lettuce and toss together. Serve with the sweet potato gratin, garnished with the coriander leaves.