Creamy asparagus soup - Mayo Clinic

Ingredients

• 2 cups peeled and diced potatoes
• 1/2 pound fresh asparagus, cut into 1/4-inch pieces
• 1/2 cup chopped onion
• 2 stalks celery, chopped
• 4 cups water
• 2 tablespoons butter
• 1/2 cup whole-wheat flour
• 1 1/2 cups fat-free milk
• Lemon zest, to taste
• Cracked black pepper, to taste