Fill large frying pan with salted water and bring it to a boil. Trim off the woody portion of the asparagus spears, and place the asparagus in the boiling water. Sprinkle with salt and cook for 2 minutes, or until the asparagus is crisp-tender. Drain. Submerge the asparagus in a large bowl of ice cold water to cool it completely. Drain again, and dry the asparagus with paper towels.
In a small saucepan, combine the vinegar and shallots and bring to a simmer over medium heat. Remove the saucepan from the heat and allow to cool. Strain the vinegar into a bowl, reserving the shallots separately.
Slowly add the grapeseed oil and olive oil to the vinegar, whisking constantly to blend. Whisk in the parsley, and season the vinaigrette with salt and pepper to taste.