Heat the oven to 200C/fan 180C/gas 6. Toss the potato wedges with 1/2 tbsp olive oil. Put on a baking tray and sprinkle with salt. Bake for 20-25 minutes until tender.
Meanwhile, mix together the pork, curry paste, grated onion and half the coriander. Season and form into 4 burgers. Brush the burgers with a little oil then grill or griddle for 5-6 minutes each side until they are cooked through.
For the mango salsa, mix the mango, chilli and the rest of the coriander with the lime juice. To serve, put a burger on top of some little gem leaves and spoon over some salsa. Serve with the sweet potato wedges.