Place the grated sweet potato, onion, and apple into a cheesecloth and squeeze out all excess liquid.
Transfer the mixture to a bowl and add the egg, flour, garam masala, chilli flakes, and salt. Mix well to combine.
Heat 1 cm of oil in a medium pan to 180°C.
Using a large spoon, scoop spoonfuls of the mixture, slightly flatten, and carefully place into the hot oil. Fry for a couple of minutes on each side until golden and crispy.
Serve the rosti on a plate with a dollop of crème fraîche and garnish with coriander leaves.
