Can one eat pickles on Rosh Hashana?
We avoid eating on Rosh Hashana foods that were cooked in vinegar or has an overall vinegar taste. This would include most pickles as they are pickled in vinegar.
The fact that it has a pleasant taste would not be a reason to be able to eat it on Rosh Hashana, as long as overall the vinegar is detectable, it should be avoided.
See here regarding eating foods that contain vinegar but it’s not detectable on Rosh Hashana: