I believe I got this from the Cook's Illustrated Family Cookbook which I checked out of the library a while back. It was served over a salad of lettuce, cherry tomatoes, crumbled bacon, and diced avocadoes. Mmmmmmmm. Of course it also works on any less carefully constructed salad that you have thrown together with whatever happens to be in the fridge also.
3/4 c. olive oil
6 tablespoons sour cream or mayonnaise
3 tablespoons lemons juice
4 teaspoons Dijon
1 tablespoon white wine vinegar
3 cloves garlic, minced
1/2 teaspoon salt.
1/2 teaspoon pepper
Whisk all together. Makes 1-1/2 cups dressing.