Leeks with Vinaigrette

At one time leeks were called the poor man’s asparagus. This may still be true in France, where asparagus have a short season and come to market fat and white and tied up with purple ribbon, and sell for a small fortune. But in America the reverse seems to be true. Asparagus have lost their cachet and can be found not just in spring but year-round, even at Christmastime dinners, while leeks, which like shallots still have gourmet-cook connotations, remain pricey. And unless my asparagus are