Chop trimmed asparagus spears into thirds, on the diagonal.
Bring a large pot of water to a boil. While water is coming to a boil, prepare an ice bath by filling a large bowl with water and lots of ice.
Blanch asparagus: add spears to boiling water and let cook for 1-2 minutes. Use a slotted spoon or tongs to remove from the boiling water and transfer spears immediately into the ice bath. Let the asparagus chill in the ice water for a few minutes then remove with the slotted spoon or tongs. Transfer asparagus to a large plate lined with a clean kitchen towel to dry.
In the meantime, prepare the rest of the salad by whisking together the dressing ingredients: lemon juice, dijon mustard, olive oil, feta, garlic, honey, pepper and sea salt.
Grab a large bowl and gently toss together blanched asparagus spears, red onion, parsley and dressing. Serve salad with 1/4 cup feta on top.