There's something comforting about seeing a big man behind the grill. Frankie is big. So are his sandwiches, all 77 varieties from around the country. And addictive, especially the Philly cheese steak, with a side of hot peppers. Maybe that's why the inside of Frankie's always looks like an episode of Hill Street Blues. Cops in uniform chowing down medianoches or muffulettas. Plainclothes guys scarfing pastrami, betrayed only by the guns they lay on the table while they eat. "It looks like a vice squad exploded in here," one customer was heard to remark recently.