Place some ice cubes into a large bowl and fill with water. Set to one side.
Set a medium pot of water on the stovetop and bring to a boil.
Snap the woody ends off of the asparagus spears and discard. Cut the spears into smaller pieces, about 1½ to 2 inches in length.
Add the chopped asparagus to the boiling water. Blanch for 20 to 30 seconds, drain, then place into the bowl of iced water.
Let the asparagus sit in the cold water for a minutes, then drain and let drip dry.
Whisk together all of the ingredients for the lemon dressing.
Place the asparagus in a serving bowl, and crumble in the feta cheese. Pour over the lemon dressing and toss together to serve.