- 1 1/2 tablespoons Sherry wine vinegar
- 1 1/2 teaspoons Dijon mustard
- 1 1/2 teaspoons chopped fresh chives
- 1 1/2 teaspoons chopped Italian parsley
- 1 teaspoon minced shallot
- 1 teaspoon chopped fresh tarragon
- 1/2 cup extra-virgin olive oil
- 4 4- to 5-inch-diameter portobello mushrooms, stemmed
- 1/3 cup extra-virgin olive oil
- 4 7- to 8-ounce skinless cod fillets
- Quick-cooking flour (such as Wondra)
Preheat oven to 400°F. Wrap garlic in foil. Place foil packet directly on oven rack and roast garlic until tender, about 40 minutes. Cool garlic. Peel and finely mash enough garlic cloves to measure 1 tablespoon packed. Place mashed garlic in heavy small saucepan. Add vinegar, mustard, chives, parsley, shallot, and tarragon. Gradually whisk in olive oil. Season vinaigrette to taste with sea salt and pepper. DO AHEAD Vinaigrette can be made 1 day ahead. Cover and refrigerate.
Preheat oven to 400°F. Brush mushrooms all over with olive oil. Place mushrooms, rounded side down, on foil-lined baking sheet. Sprinkle with sea salt and pepper, then chopped garlic. Arrange 2 rosemary sprigs and 2 thyme sprigs on each. Roast mushrooms until tender, about 25 minutes.
Sprinkle fish with sea salt and pepper; dust lightly with flour. Heat canola oil in heavy large skillet over medium-high heat. Add fish and sauté until brown and just opaque in center, about 5 minutes per side.
Whisk vinaigrette over low heat to warm slightly. Thinly slice each mushroom on slight diagonal; overlap slices in row on 1 side of each plate. Spoon vinaigrette onto opposite side of plate; top with fish.