Char with Pea Sprouts and Forest Mushrooms

Name: Char with Pea Sprouts and Forest Mushrooms
Ingredients: 5 tablespoons plus 1 teaspoon olive oil; 12 ounces mixed fresh flavorful mushrooms (black trumpet, chanterelle, cremini, hedgehog, mousseron, oyster, and portobello), chopped into bite-size pieces; Salt and ground pepper to taste; 2 tablespoons chopped shallots; ½ tablespoon minced fresh garlic; 3 tablespoons all-purpose flour; ¼ cup champagne or white wine vinegar; 3 cups chicken or vegetable stock; Fresh tarragon to yield 1 tablespoon chopped, held whole; 4 skin-on Arctic char fillets, about 6 ounces each (cod will work as substitute); 6 cups (about 10 ounces) pea sprouts (if unavailable, substitute chopped spinach or escarole)