Cut the pak choi into strips and set aside the green part. Chop the garlic cloves and coriander, dice the sweet potatoes. Halve the onion and cut into slices.
Heat some oil in a large saucepan and sweat the garlic until translucent. Add the ginger and curry paste and sweat too. Deglaze with the vegetable stock. Add the sweet potato cubes and the white part of the pak choi and cook for 5 minutes.
Add coconut milk, soy sauce and lemon juice and stir everything well. Add the noodles and the green part of the pak choi and bring to the boil for another 3 minutes.
Spread on bowls and garnish with coriander, bean sprouts and onion slices.