Spinach Salad with Bosc Pears, Cranberries, Red Onion, and Toasted Hazelnuts

INGREDIENTS

• 2 teaspoons whole-grain mustard
• 1/2 cup extra-virgin olive oil
• 1 cup thinly sliced red onion
• 2/3 cup hazelnuts, toasted (see Cook's Notes) and chopped
• Freshly ground pepper
• 2 firm but ripe Bosc pears (do not peel), quartered lengthwise, cored, and cut into long, thin slices
• 2 tablespoons balsamic vinegar
• 1 teaspoon kosher or sea salt
• 8 cups lightly packed fresh baby spinach leaves, stemmed if needed
• 1 teaspoon sugar
• 1/3 cup sweetened dried cranberries