Wash, pat dry, and then weigh the duck. I did all 4 of mine at the same time because I was placing them in the same bag to cure. If you will be placing them in different bags to cure then weight each one separately and jot that weight down.
Once you have the weight Calculate your ingredients based off of the weight that you wrote down.
Rub your seasonings into your duck, massaging it well and place in a vacuum bag removing all the air. Place in your fridge for 5 days to 8 days (Depending on the thickness of your duck breast. If you want to calculate the time needed to cure you can click the following link:
After the duck has cured remove from the fridge and either rinse off or pat dry. Wrap in cheese cloth or collagen sheets then tie a few knots over the duck to hold it all in place and to hang later.
Weigh your duck and record your green weight. I like to record my target weight as well (I generally shoot for 38%-40% weight loss)
Hang in a drying chamber at 55F with a humidity at 80%.
The amount of time necessary to dry will be determined by how much fat your duck has, how big the breast is, the temperature in your drying chamber, and the humidity in your drying chamber. The goal is to slow down the drying as much as you can to really develop the flavor of the prosciutto.