grill pan, umeboshi plum vinegar

Question

just to repeat a question, i wanted to know if there's a way to kosher a circulon grill pan. it's used for grilling fish and vegetables on the stovetop, and i'm not sure if i kosher it for pesach using hagala (which i already did), or if i should be doing it another way, or even if it can be koshered at all. 2. do you know if eden ume plum vinegar is good for pesach. ingredients: japanese ume plum, sea salt, shiso(perilla leaves). thank you again for all your help, and have a happy Pesach.