The French say Bon appétit! to wish others to enjoy their meal. In Spanish, Italian, German, and Portuguese, the expressions are somewhat similar: Spanish: Buen provecho!; Italian: Buon appetito!; German: Guten Appetit!; and Portuguese: Bom apetite!.
The Japanese phrase meshiagare (召し上がれ) is used to indicate that food is ready to eat.
It is often said by a chef, server, or host.
After hearing meshiagare, it is customary to respond with itadakimasu (いただきます).
Iranians say noosh e jaan (نوش جان), meaning may it nourish your soul.
(And yes, the noosh part is the same noosh that is a part of my name, NooshAfarin.)
To those of you who are brave enough to try any of the recipes in The Petal's Whisper:
noosh e jaan!