I enjoy spicy foods. Can I have spicy foods on Rosh Hashona?
For example: horseradish on gefilte fish, zchug with the meat, onions in the chicken dish, etc.
There is an ancient custom, which is mentioned by the Geonim, to avoid eating sour foods on Rosh Hashanah (such as chicken in vinegar). This custom is mentioned by the Ben Ish Chai (Nitzavim 5), the Chida, and also by the Peri Megadim and Mishnah Berurah (583), and by the Chayei Adam (139:6).
However, there is room to distinguish between sour foods and spicy foods. Sour foods are a symbol of something that has gone bad — such as wine that has gone sour — but spicy foods are fine. Therefore, it appears that there is nothing wrong with spicy foods.
It is noteworthy that the Mateh Efraim (583:3) mentions bitter foods together with sour foods — but bitter foods are not spicy foods, and there does not appear to be any problem in spicy foods.