Preheat the oven at 200ºC (392ºF).
Let's prepare the first sauce. Chop 2 garlic cloves and 10 g of coriander. In a saucepan, pour 30 g of olive oil, the garlic and the coriander. Heat it in low fire (about 4-5 minutes)
Prepare two aluminium foils. In each one, place a hake loin that was seasoned with salt and black pepper in each side of it. Baste with the olive oil, garlic and coriander sauce. Close the aluminium foils. ATTENTION: do not close all the orifices.
Place the curlpaper in an oven board. Let it cook for 15-25 minutes. At the same time cook the sweet potato in water, until is 3/4 cooked.
When everything is ready, prepare the second and final sauce. Do the first step again.
Dispose the sweet potato and the hake loin in a prate. Pour the coriander and garlic sauce over them.