- Melt butter in a heavy large saucepan over medium-high heat. Add garlic and saute 30 seconds.
- Add onion and saute another 2 minutes or so.
- Then add mushrooms and saute until tender, about 10 minutes.
- Don't worry if the mixture seems too dry.
- Reduce heat to medium, then add flour and stir another minute. Add white wine and cook until mixture thickens, stirring frequently--about another 2-3 minutes.
- Mix in sour cream, and season to taste with salt and pepper.
- Add cooked linguine and toss to blend linguine with sauce.
- **Adapted from a recipe in _Bon Appetit_.