Whisk lemon rind and juice, honey, capers, mustard, salt and pepper in bowl. Whisk in oil in thin stream until blended.
Place peppercorns, lemon rind and juice, and bay leaf in 10-inch skillet. Add water to depth of 1-1/2 inches. Bring to just under simmering, so bubbles form on bottom of pan, but do not break surface. Add salmon; poach, uncovered, not letting water simmer, 7 to 9 minutes, until cooked through. Remove fish to pie plate; let cool slightly.
Fill large pot with tightly fitting lid with 1 to 2 inches of water. Place steamer insert in bottom; bring water to a boil. Trim tough asparagus ends, removing about 1 inch. Rinse asparagus; add to insert; steam, covered, 8 to 9 minutes or until crisp-tender, depending on thickness. Remove from pot; let cool.
Toss asparagus with 1/4 cup dressing in large bowl. Set aside 32 stalks. Slice remaining stalks in thirds. Mix sliced asparagus and greens in large bowl. Using fork, flake salmon. Add to greens with 1/4 cup of remaining dressing; season with salt; toss.
On each of 4 plates, create a square with reserved asparagus, using 8 stalks per plate.
Pile about 3 cups salad in center of each square. Serve with the remaining dressing, if you wish.