Season the duck legs with the salt and place them skin side down in a cold 28cm or 11" frying pan. Pop them on the hob, set the temperature to low-medium and put them on the heat and cook for 15-20 minutes.
Do not move them during this cooking phase; you want to render out lots of the fat and get some really nice crispy skin.
Cut the onion in half, peel it and then slice it into 2-3mm (⅛") thick half-moon shapes.
Zest the orange into a medium mixing bowl, then cut the orange in half and squeeze the juice from half of it into the bowl.
Add the pomegranate molasses, brown sugar, warm water and star anise to the bowl and mix well.
By now, the duck should have freed itself from the base of the pan and browned up nicely. Flip it and cook it for 5 more minutes.
Remove the duck legs, set them aside and add the onions to the pan and cook them for 5 minutes in the duck fat, stirring regularly.
Return the duck to the pan, skin side up, and pour over the sauce.
Cover with a lid and transfer to the oven and cook for 90 minutes at 160°C or 320°F.
Take the pan out of the oven, place it on the hob, and remove the duck and set it aside. Turn the heat to medium and cook for 7-10 minutes to reduce the sauce before serving.