4 teaspoons extra-virgin olive oil, divided
10 ounces mushrooms, sliced
2 cups thinly sliced leeks, white and light green parts only (about 2)
1/4 cup brandy or dry vermouth
1/4 cup reduced-sodium chicken broth
3 tablespoons reduced-fat sour cream
1 tablespoon chopped fresh parsley
1/2 teaspoon salt, divided
Freshly ground pepper to taste
1 pound large dry sea scallops
Heat 2 teaspoons oil in a large skillet over medium-high heat. Add mushrooms; cook, stirring occasionally, until they begin to give off liquid, about 3 minutes. Stir in leeks; cook, adjusting heat to prevent scorching, until the vegetables are very tender and the leeks are starting to brown, about 8 minutes. Add brandy (or vermouth) and broth; cook until reduced and thickened, about 30 seconds. Remove from the heat and stir in sour cream, parsley, 1/4 teaspoon salt and pepper to taste. Cover and set aside.
Pat scallops dry and sprinkle with the remaining 1/4 teaspoon salt and pepper. Heat the remaining 2 teaspoons oil in a large nonstick skillet over medium-high heat. Add the scallops and cook until golden brown, 2 to 3 minutes per side. To serve, place some of the leek-mushroom mixture on each plate and top with scallops.