Vinaigrette: Heat large skillet, preferably cast iron, over medium-high heat. Add tomatoes and cook, turning with spatula, until blackened on all sides. Remove from skillet. Cool, then chop coarsely. In medium bowl, whisk olive oil, vinegar, salt, and pepper until thickened. Add tomatoes. Serve at room temperature. Trout:Remove the skin and bones of the trout; set aside. In bowl, whisk mayonnaise, egg, cream, green onions, parsley, mustard, Worcestershire sauce, Old Bay seasoning, ground red pepper, and black pepper. Add trout and soda crackers, then stir gently to combine without breaking up trout completely. Shape trout mixture into twelve 1 1/2-inch diameter patties; coat with bread crumbs. Cover and chill at least 1 hour. Heat butter in heavy skillet over medium. Add trout cakes and cook 3 to 4 minutes on each side or until golden brown. Arrange a few asparagus spears on each warm plate; drizzle with tomato vinaigrette. Top with trout cakes. Toss greens with about 1/3 cup vinaigrette; spoon onto each plate.