1. Boil, steam, or bake the asparagus until crisp-tender. Transfer to a heated platter and keep warm in an oven set at 200°.
2. In a small saucepan, combine the wine, butter, and tarragon. Cook over medium heat until reduced by half. Remove from the heat and gradually whisk in the mayonnaise. Stir over low heat to warm gently. Sprinkle the asparagus spears with salt and pepper, then pour the sauce over the spears. Serve immediately.