Asparagus with Walnuts and Vinaigrette

Description
Perfect in springtime, asparagus' natural sweetness contrasts beautifully with this tart vinaigrette.

Ingredients

 * 1 pound fresh asparagus, trimmed
 * 1/4 small onion, very finely chopped
 * 2 tablespoons white wine vinegar
 * 1 teaspoon Dijon mustard
 * 1/2 packet sugar substitute
 * 1/2 teaspoon salt
 * 1/4 teaspoon pepper
 * 1/4 cup olive oil
 * 1 pinch salt
 * freshly ground black pepper
 * 4 cups spring salad mix (mesclun)
 * 1/4 cup toasted walnuts, or almonds

Directions
1. Steam asparagus until crisp-tender. Drain, and pat dry with paper towels. Set aside. 2. Combine shallot, vinegar, mustard and sugar substitute, salt and pepper in a mixing bowl. Gradually whisk in oil. 3. Divide lettuce on 4 plates; arrange asparagus on top and drizzle with vinaigrette. Sprinkle with walnuts.