Place the cheese in a large bowl. Gradually add 1/2 cup of boiling water, whisking constantly. Slowly drizzle in the olive oil, whisking constantly. Taste. Season with salt and pepper.
lay the spears flat on a cutting board and trim off the woody ends with a sharp knife. Using a vegetable peeler and pressing hard, shave each spear into long, thin ribbons. (If necessary, cut the final layer of each stalk into thin strips—it might be thicker than the other ribbons, which is just fine.) Trim off each tip and cut lengthwise in half.
Toss the asparagus pieces with several tablespoons of the dressing. Add arugula and toss again. Season with more salt and pepper if necessary.
Serve with bruschetta or over flatbread or pizza