Alternately thread peppers, cucumber, zucchini and cherry tomatoes onto skewers.
Arrange skewers on platter, wrap in plastic wrap or place in storage container with tight-fitting lid. Can be refrigerated up to one day.
In small bowl, whisk together vinegar, mustard, salt and pepper until blended.
In thin, steady stream, whisk in oil until blended; stir in tarragon.
Transfer vinaigrette to small container with tight-fitting lid. Serve skewers with vinaigrette.