From Bon Appetit, March 2008. Since asparagus is rather low in potassium, take advantage of its being in season during the spring.
3 tablespoons fresh lemon juice
1 tablespoon red wine vinegar
1 teaspoon Dijon mustard
Pinch of kosher salt
1/2 teaspoon freshly ground black pepper
3/4 cup extra-virgin olive oil
3 lbs. medium asparagus, trimmed
4 cups thinly sliced green onions
3 cups 1/4-inch cubes peeled seeded Kirby or English hothouse cucumbers
1 tablespoon chopped fresh Italian parsley
1 tablespoon chopped fresh chervil
1 tablespoon chopped fresh chives
1 tablespoon chopped fresh mint
2 teaspoons chopped fresh tarragon
Dressing: Whisk first 5 ingredients in small bowl. Gradually whisk in oil. (Can be made 1 day ahead. Cover and refrigerate. Bring to room temperature and rewhisk before using.)
Salad: Fill large bowl with lightly salted ice water; stir until salt dissolves. Cook asparagus in large pot of boiling water until crisp-tender, about 3 minutes. Drain, reserving 3 cups cooking liquid. Transfer asparagus to bowl of ice water to cool. Place green onions in another large bowl; pour hot reserved asparagus cooking liquid over onions and let stand until cool, about 30 minutes. Drain asparagus and green onions well. Transfer onions to clean kitchen town and squeeze dry.
Combine green onions, cucumbers and herbs in mixing bowl. Add dressing; toss to coat. Season with salt and pepper, if desired.
Arrange asparagus on platter. Spoon cucumber mixture over and serve.