Peel and finely grate the onion. Wash the coriander, dab dry, put some stems aside for garnishing. Pluck the remaining coriander from the stems, chop very finely. Knead coriander, minced meat, onion, egg yolk and breadcrumbs, season with salt, pepper and cumin.
Form small dumplings from the minced meat mass. Heat the oil in a pan. Fry the dumplings for 4-6 minutes, turning them over and taking them out. Peel and dice the garlic. Remove the outer leaves from the lemon grass.
Wash the lemon grass, dab dry, tap a little with the back of a knife. Peel and chop the ginger. Clean, wash and cut leek into rings. Remove any pumpkin seeds from the pumpkin. Wash and peel the pumpkin, dice the flesh.
Wash the chilli, remove the stem, cut in half lengthwise, remove the seeds and cut the pod into pieces. Peel, wash and chop the potatoes. Heat the frying set again. Fry pumpkin, potatoes and leek for 2-3 minutes.
Add the garlic, chilli pepper, lemongrass, ginger and curry paste to the pan and continue to fry for about 3 minutes. Deglaze with coconut milk and broth. Bring to the boil, season to taste with salt, a little sugar and pepper.
Add the meatballs and simmer for about 5 minutes at low heat. Arrange curry, garnish with coriander.