1. Heat oil in medium saucepan over medium heat until shimmering but not smoking; add shallots and cook, stirring frequently, until softened and beginning to color, about 1 1/2 minutes. Add wine and 1 tablespoon lemon juice, increase heat to high, and bring to boil; boil until reduced to 3/4 cup, 3 to 5 minutes. Remove saucepan from burner, whisk in butter, capers, parsley, and if desired, remaining 1 tablespoon lemon juice until combined; season to taste with salt and pepper. Cover to keep warm and set aside, stirring once after about 1 minute.

2. To serve, stir sauce to recombine and spoon 1/2 cup over fish. Serve immediately with lemon wedges, passing remaining sauce separately.

Makes about 1 cup