What is the Etymology of “Krepel”?
Krepel is a 3 cornered stuffed piece of dough that we eat on Purim, Hoshana Rabah, and Erev Yom Kippur.
I don't know.
Wikipedia claims (without any source given) that Yiddish קרעפל is "probably derived from the Old High German kraepfo meaning grape. The Middle English word grapple is related (from a grape vine hook)", which seems to have multiple mistakes (if we believe the Online Etymology Dictionary), but may be correct in that Yiddish קרעפל is related to Germanic words meaning "hook".
R'Alex's answer suggests a relation to French crêpe, which is purportedly, and again purportedly, from Latin crispus, "curled", via Old French. While this may be possible, of course, this layman would sooner believe a derivation from Germanic sources.
Update: I've now asked for assistance from someone on Wiktionary who actually knows some etymology, at least in Germanic languages, and in response to my request he's posted the etymology to Wiktionary. He says it's actually from (not, as I had suspected, cognate to) German Kräppel, "a fried pastry", related to Krapfen, etc. (See there for all the gory details.)
ספר הפרנס סימן קיב לקשנוס שקורין קרעפליכה
The earliest mention of kreplach seems to be a 13th century Judeo-German writer called the Parnas. It reads luchsohns which are called krepalicha. So it would be Old French or High German.