Mandu dumplings
Korean dumplings filled with minced meat, tofu, vegetables or kimchi, then steamed, boiled or pan-fried.
Frozen mandu are sold in any Asian grocery and increasingly in the freezer section of larger supermarkets. Wrappers for making your own are also found frozen at Asian groceries.
Substitute:
Japanese gyoza or Chinese jiaozi are very similar and can be used as they are; their filling is usually seasoned a little differently and rarely contains tofu or glass noodles.