Dry pickle slices with paper towel. Dip slices in tempura batter mixed with mustard and then into a mixture of eggs and milk. Generously toss to coat with bread crumbs. Heat 4 inches of vegetable oil in a pot over medium-high heat. Gently place 5-10 battered pickle slices in hot oil. Fry in batches 1-2 minutes, or until golden. Drain on paper towel. Serve warm with Dijon mustard.