Spinach-Pear Salad with Mustard Vinaigrette

2 Bosc pears, cored and thinly sliced
1 (6-ounce) package fresh baby spinach
3 tablespoons water
2 tablespoons balsamic vinegar
1 teaspoon sugar
5 teaspoons extra virgin olive oil
1½ teaspoons stone-ground mustard
¾ teaspoon salt
½ teaspoon coarsely ground black pepper
¼ cup (1 ounce) shaved Parmigiano-Reggiano cheese

1. Combine pear slices and spinach in a large bowl.
2. Combine water and the next 6 ingredients (through pepper).
3. Drizzle vinaigrette over salad, and toss gently to coat. Sprinkle with cheese.