In a small bowl, whisk balsamic and red wine vinegars, Dijon mustard, salt and pepper. Slowly whisk in oil in a thin stream. Stir in chervil and shallots. Cover and set aside until ready to use.
Steam asparagus until tender, about 6 minutes.
Arrange asparagus and tomatoes on a large platter. Sprinkle with feta cheese. Drizzle with half of the dressing. Serve the remaining dressing on the side. Note: This may be served warm, room temperature or chilled.
Makes 8 servings.