1. Cook pasta according to package directions.

2. Melt butter in a saucepan over medium heat.

3. Add onion; cook until tender.

4. Stir in salt, flour, and a dash of pepper

5. Add milk.

6. Cook and stir until thickened and bubbly.

7. Place sour cream in a bowl; add 1 cup of hot mixture to sour cream and combine.

8. Return sour cream mixture to saucepan.

9. Stir in tuna and white wine.

10. Heat through, but do not allow to boil.

11. Serve over pasta.