C.J. Gerdes, the third-generation chef and owner of Casamento’s restaurant, fries a lot of oysters. But he doesn’t use one of those new-fangled electric fryers. Nope, he plunges the cornflower-coated bivalves into two-gallon-size steel saucepans filled with sizzling liquid lard. Juggling five such saucepans atop a tall gas…