Warm Goat Cheese Salad

In a small bowl, whisk vinegar with mustard. Slowly add oil in a steady stream, whisking constantly. Season with salt and pepper. Place greens in a large bowl.

Meanwhile, heat broiler. Arrange baguette slices on a baking sheet; top each with a goat cheese round. Toast until bread is golden brown and cheese has started to melt, 2 to 3 minutes. Drizzle greens with vinaigrette; toss to combine. Divide among four plates. Place three toasts on each salad. Serve immediately.