To prepare mayonnaise, combine first 5 ingredients in a small bowl. Cover and chill.
To prepare tuna cakes, combine tuna and next 8 ingredients (tuna through salt) in a bowl; stir until well-blended. Divide tuna mixture into 4 equal portions; shape each into a 1/2-inch-thick patty. Dredge patties in 2 tablespoons breadcrumbs.
Heat oil in a nonstick skillet coated with cooking spray over medium-high heat until hot. Add patties, and cook 3 minutes on each side or un-til browned. Serve with mayonnaise.