1 tablespoon Sherry wine vinegar

1/2 teaspoon Dijon mustard

3 tablespoons extra-virgin olive oil

3 tablespoons butter, melted, divided

2 ounces sliced pancetta (Italian bacon)

1 pound thick asparagus, tough ends trimmed

4 1/2-inch-thick slices challah, brioche, or other egg bread, halved lengthwise

Preheat oven to 450°F. Whisk vinegar and mustard in small bowl. Gradually whisk in oil and 1 tablespoon melted butter. Season vinaigrette with salt and pepper. Place pancetta on rimmed baking sheet. Bake until crisp, about 7 minutes. Meanwhile, cook asparagus spears in large skillet of boiling salted water until tender, about 5 minutes. Drain asparagus; pat dry. Transfer warm asparagus to large bowl; add vinaigrette and toss to coat. Season to taste with salt and pepper. Toast bread slices and brush with remaining 2 tablespoons melted butter. Arrange 2 toasts on each of 4 plates. Divide pancetta, then asparagus among toasts. Drizzle any remaining vinaigrette over and serve.