For the sauce:
For the sauce: mix the yogurt, coriander, lemon juice and mustard in a bowl, stir well, and season to taste with salt, pepper and olive oil. Add about 1 oz of pomegranate and stir.
Slice the sweet potatoes into about 0.4-inch slices. Put in a bowl and mix with olive oil, salt, pepper and merken.
Put the sweet potatoes in an oven tray, taking care not to stack them. Bake at 390°F in a preheated oven for about 20 minutes or until brown and cooked (they feel soft when poked with a fork).
Take out of the oven and sprinkle the remaining pomegranate arils on top. Serve with the sauce.
*You can prepare the sauce 1 day before serving and keep it refrigerated.