Dry the duck legs thoroughly, then pierce the skin all over with a sharp paring knife and trim any excess fat from the underside of the leg.
Cut the onion into 1-1½cm or (½") thick slices, then peel off the skin from the outside.
Peel the garlic cloves and slice them as thinly as you can.
Cut the dried apricots in half.
Mix together the harissa paste, water and lime juice in a small mixing bowl.
Heat the base of a small tagine over a medium-high heat, and whilst it is heating, rub the duck legs with the cooking oil and salt.When the tagine is hot, sear the duck on the skin side only until it is golden. You will need to do these separately, then remove and set them aside. This will take 2-4 minutes per leg, depending on the temperature of your tagine base.
Reduce the heat under the tagine to low and layer up the ingredients in this order: onions to form a base, then sprinkle over the garlic, almonds and dried apricots.
You can drain out some of the duck fat before you start layering up, if you want. I never do!
Add the duck legs skin side up, then pour over the harissa paste mix and sprinkle over half of the sumac, add the lid and cook on a low temperature for 40-45 minutes.
Remove the lid and sprinkle with the remaining sumac and lots of coriander before serving.