An addition or accompaniment added to a main item; e.g. a garnish, side dish, or something included with a gift.
刺身には大根の千切りが添え物として出されることが多い。
Sashimi is often served with shredded daikon as a garnish.
プレゼントにはメッセージカードを添え物として付けた。
I included a message card as an accompaniment to the gift.
この料理は主菜のボリュームがあるので、添え物は軽めにした方がいい。
Because the main dish is substantial, it's better for the accompaniments to be lighter.