Melt butter or margarine in a medium-sized saucepan over medium heat. Add flour, salt and pepper and stir until flour is slightly browned.
Remove from heat and slowly stir in milk until flour is incorporated. Return to heat and bring to a boil, stirring, for 1 minute, until thickened.
Add drained tuna and peas and heat thoroughly, without boiling.
Ladle over toast on plate or bowl and serve warm.
Submitted by: Catwuvr