Preheat oven to 375F. Prepare fresh pomegranate juice, if necessary.** Rub each tenderloin with salt, pepper, thyme and rosemary. Wrap each tenderloin with prosciutto and tie at intervals with string. Over medium-high heat on the cooktop, brown tenderloins in an ovenproof skillet. Reduce heat to low; add chicken broth and pomegranate juice. Cover and bake until pork is done or meat thermometer inserted in center is 165F, about 25 to 30 minutes. Prepare marmalade while tenderloins are baking. Remove string and slice each tenderloin.
**Prepare fresh pomegranate arils, if necessary.
*** Reserve 1 cup of the arils from fruit and set aside. (Refrigerate or freeze remaining arils for another use.) Heat a skillet over medium-high heat; add water and thawed onions. Reduce heat to low and cook until soft, about 15 to 20 minutes. Add salt, honey and white wine vinegar (or lemon juice and lemon zest). Cook until onions are glazed and sauce is thickened. Stir in arils and serve this pomegranate recipe hot with pork.
*If using fresh pearl onions, remove skin by blanching in a pot of boiling water and then cooling in a bowl of ice water. Slip off onionskins and proceed with recipe.
**To prepare fresh pomegranate juice, cut 2–3 large POM Wonderful Pomegranates in half and juice them with a citrus reamer or juicer. Pour the mixture through a cheesecloth-lined strainer or sieve. Set the juice aside.
***To prepare fresh pomegranate arils, score 1 large POM Wonderful Pomegranate and place in a bowl of water. Break open the pomegranate under water to free the arils (seed sacs). The arils will sink to the bottom of the bowl and the membrane will float to the top. Sieve and put the arils in a separate bowl.