The night before: Add the buttermilk to a large bowl with the frog legs. Cover the bowl and refrigerate overnight (at least a good 10 to 12 hours).
The day of: Mix the flour, salt and white pepper in a large bowl. Dredge the legs, in the flour mixture, coating them completely. Shake off all of the excess flour. In a deep-fryer or heavy-bottomed pot, heat enough oil to come halfway up the sides of the pot, to 375 degrees F.
Add the frog legs to the oil and fry until golden brown, about 3 to 5 minutes. Transfer to a serving platter and serve with the mayo.
In a large saute pan over low heat, add the wine and simmer to reduce it to a syrup. Cool and combine with mayonnaise in a small bowl. Season to taste, refrigerate until needed.
Recipe courtesy of Matt Buschle, owner of Virgil's Cafe in Bellevue, KY