There were no new recipes to purchase in Version 5.7 (although we just got 3 new recipes by mail today). Skirk's specialty dish is made from "Grilled Fish in Mint Sauce". It is a recipe that we first found in Natlan with Cipac at the Stadium of Sacred Flames. "... Where did she even catch this fish? A sudden and unsettling suspicion arises... S—Surely not..."
