. Combine olive oil, vinegar, 1/4 teaspoon salt, and 1/8 teaspoon pepper in a small nonreactive saucepan over medium-high heat. Stir in roasted red pepper, onion, and garlic and bring to a boil. Reduce heat to maintain a low simmer. Place washed and dried greens in a large bowl.

Select a large sauté pan with a tight-fitting lid. Smear with butter and scatter chopped shallots on top. Lay sole fillets on a work surface. Spread chopped tarragon over each fillet. Season with remaining salt and pepper. Beginning with wide end, roll up fillets and place in pan, with ends tucked underneath. Sprinkle white wine around fillets, cover, and place over medium-high heat. As soon as juices begin to run and bubble, reduce heat to low and cook, covered, for 3 minutes. Remove from heat. Keep covered.

Pour hot vinaigrette over greens and toss briskly. Divide between two large plates, mounding slightly. Place sole roulades on top and spoon any accumulated juices over them. Serve at once.