Spinach and Prosciutto Salad With Apple-Onion Vinaigrette

3 tablespoons olive oil

1 small onion, finely diced (¾ cup)

1 large tart apple, such as Granny Smith, peeled, cored and cut into ¼-inch dice

1 tablespoon maple syrup, or more to taste

Kosher salt

Freshly ground black pepper

3 tablespoons apple cider vinegar

About 10 ounces fresh baby spinach

6 thin slices Prosciutto di Parma (about 3 ounces total)

1/3 cup chopped toasted walnuts (see note)

Heat the oil in a large nonstick saute pan over medium-high heat. Add the onion; reduce the heat to medium and cook for 3 to 4 minutes, until the onion just starts to soften, then stir in the apple. Cook, stirring every minute or so, for 5-7 minutes, until the apple softens. It’s OK if the onion browns a bit. Remove from the heat and transfer to a small bowl.

Mix in the maple syrup, then season with salt and pepper to taste. Let cool for 15 minutes, then stir in the vinegar. Taste, and adjust the seasoning as needed.

Lay the spinach leaves out on a large shallow bowl or platter or individual shallow bowls. Tear the prosciutto into pieces about 2 inches long and 1 inch wide; distribute over and among the spinach leaves. Sprinkle the walnuts over the salad. Spoon the vinaigrette over and toss to coat evenly.

Serve immediately.

Serves four.

Cook’s note: Toast the nuts in a small, dry skillet over medium-low heat for a few minutes until fragrant and lightly browned, shaking the pan as needed to avoid scorching. Let cool before using.

Nutrition values per serving: 260 calories, 19 g fat (3 g saturated), 15 g carbohydrates, 3 g fiber, 8 g sugar 10 g protein, 10 mg cholesterol, 700 mg sodium.

Stephanie Witt Sedgwick for The Washington Post