Tuna Pie with Cheese

3 tbsp butter
1/2 cup sliced green pepper
2 slices of onions
6 tbsp of flour
1/2 tsp salt
2 cups milk
2 cans (6 1/2 oz) tuna, drained and flaked
1 tbsp lemon juice
Cheese

Melt butter, add green peppers and onions and cook until onions are golden brown. Add flour and salt and cook until well blended; add milk slowly, stirring constantly until thick and smooth.
Add tuna and lemon juice; put in greased baking dish and cover with cheese whirls. Bake in a hot oven, 450° for about 30 minutes or until browned.