Blender-crumb 3 slices of bread and put into large bowl.
Blender crumb 2 slices, put on wax paper.
Put Swiss cheese into Osterizer container, cover and process at BLEND until finely grated.
Add to bowl.
Melt butter in saucepan.
Put milk, flour and seasonings into Osterizer container, cover and process at STIR until smooth.
Add to melted butter and cook over medium heat, stirring constantly, until thickened.
Add tuna and set aside.
Put two eggs, parsley and onion into Osterizer container, cover and CYCLE/CHOP onion.
Add to tuna mixture and mix briskly to blend well.
Cook over medium heat about 10 minutes, stirring constantly.
Add to crumb-cheese mixture, add lemon juice and mix well.
Refrigerate about 30 minutes.
Put remaining egg and milk into MINI-BLEND container and process at STIR until well mixed.
Shape about 1/2 cup of mixture into croquette, dip in egg, and roll in crumbs.
Set aside while oil heats.
Fill deep fat fryer or heavy saucepan to a depth of 3 inches and heat to 325°.
Fry croquettes until golden brown about 4 or 5 minutes.
Drain on paper towels and keep warm in oven while frying remaining croquettes.
Serve hot with tartar sauce.