This is a an ingredient that can be used in my other custom recipes and can be purchased from my Brazen Delivery service if you don't want to craft it. This includes a recipe that will allow your sim to create a barrel of vinegar mash from my Preserving Shelf or the Brazen Homestead Craftbooks. Once created, that barrel can be aged and vinegar can be collected from it at different stages. That can then be used as an ingredient in other recipes.
Dark Emotions Mod is a CAS trait located in the emotional category. Give your Sim this trait and they'll start to randomly experience hopelessness, bitterness, feel fucked up, and emotionally numb.