Mix 100 ml milk well with the crème fraîche.
Boil the potatoes until al dente, peel and coarsely dice. Finely chop the onion and fry in oil. Press the garlic and grate the ginger finely. Fry both briefly with the onion. Add the chilli and paprika powder, coriander, turmeric, garam masala and salt to the onions and stir-fry briefly.
Deglaze with 200 ml milk and reduce briefly. Gradually stir the crème fraîche into the curry. Add the potatoes and cook briefly.

Serve with rice or pita bread.