Formal — to staff
Restaurant · Dietary
You
すみません、この料理のだしは、かつお節を使っていますか？私は魚介類が食べられなくて。
すみません、このりょうりのだしは、かつおぶしをつかっていますか？わたしはぎょかいるいがたべられなくて。
Excuse me, does the dashi in this dish use bonito flakes? I can't eat seafood.
Romaji: Sumimasen, kono ryōri no dashi wa, katsuobushi o tsukatte imasu ka? Watashi wa gyokairui ga taberarenakute. / Reply Romaji: Hai, ippan-tekina dashi wa katsuobushi o tsukaimasu ga, kochira no ryōri wa konbu-dashi nomi desu.
Reply
はい、一般的なだしはかつお節を使いますが、こちらの料理は昆布だしのみです。
はい、いっぱんてきなだしはかつおぶしをつかいますが、こちらのりょうりはこんぶだしのみです。
Yes, general dashi uses bonito flakes, but this dish only uses kelp dashi.
Gesture & etiquette
Point to the menu item you are asking about, then make a 'no' gesture (waving hand in front of face) when saying 'taberarenakute'.
Always state your dietary restrictions clearly and politely. Understand that not all restaurants can cater to every specific request, especially for very niche ingredients like dashi components.