Step 1As each vegetable is prepared, set aside separately: Trim the stems of the carrots to one-fourth inch and cut the tips off. Peel and cut in half. Trim and peel the beets and turnips. Cut them in halves or quarters depending on their size. Trim the wax beans and haricots verts and cut into 2-inch lengths on the bias. Trim the green tops of the pearl onions to 1 inch. Barely trim the root end so that the onion layers stay intact when they are blanched. Peel the onions and leave whole. Remove the stems of the tomatoes. If the tomatoes are large, cut them in half, otherwise leave them whole. The tomatoes will not be blanched.
Step 2The day you'll prepare the salad, bring a large pot of heavily salted water to a boil. Blanch the vegetables, except for the tomatoes, separately until tender (about 3 to 5 minutes depending on the vegetable). Taste the vegetables to test if they are done. They should be tender but a little crisp. Remove with a slotted spoon and chill in ice water. Drain well in a colander and then on a clean thick towel.
Step 3Cut the pearl onions in half after they are blanched.
Step 4In a large bowl, toss all of the vegetables together with 3 tablespoons of extra-virgin olive oil. Season them with fleur de sel and pepper to taste. Squeeze the lemon over them and lightly toss.
Step 5Transfer the vegetables to a large white platter. Use a vegetable peeler to shave the pecorino over the top. Drizzle liberally with olive oil and sprinkle with snipped chives.