Flank Steak Sandwiches with Roquefort Cheese

In a small bowl, whisk togther the vinegar, mustard, tarragon, thyme, salt, and pepper. Gradually whisk in 1/3 cup of the oil until well blended. Place the flank steak in a bowl and pour all but 2 tablespoons of the vinaigrette over the meat. Cover and let marinate, turning occasionally, for 1 hour at room temperature or overnight in the refrigerator. In a food processor, puree the Roquefort, cream cheese and lemon juice until smooth. Season with pepper to taste. Scrape into a small bowl and stir in the walnuts. In a large skillet, heat 1 tablespoon of the olive oil over high heat. Add the flank steak and saute, turning once, until medium-rare, 4 to 6 minutes per side. Slice the steak crosswise on teh diagonal into thin strips. In a medium bowl, toss the sliced steak and pea pods with the remaining 2 tablespoons vinaigrette. Spread the Roquefort mixture evenly over both sides of each roll and fill with the steak and snow peas.