Eating & Cooking with Nuts and Vinegar on Rosh Hashanah? 🍎🍯

A very common question I get is using vinegar as  an ingredient for foods on Rosh Hashanah and using   nuts. So the minhag is not to eat very sharp, or  bitter, or sour foods on Rosh Hashanah. We want   our foods to be sweet, to represent our hopes for  a sweet year. And therefore the minhag is only to   not have the dish be very sharp, or very strong,  or very bitter. But to simply use vinegar as an   ingredient in the food is not a problem at all.  When it comes to using nuts, the custom is not to   use walnuts at all. That's because the numerical  value of walnuts in Hebrew is the same as sin. So   we don't use walnuts at all. Regarding other nuts,  the general custom is not to eat whole nuts, but   you can use crushed up nuts or things like that  in a recipe as long as you're not using walnuts.