This soup is a good source of potassium, vitamins A and C, iron, folate, magnesium and selenium.

In a large soup pot over high heat, combine the potatoes, asparagus, onions, celery and water. Bring to a boil. Reduce heat, cover and simmer until the vegetables are tender, about 15 minutes. Stir in the butter.

In a small bowl, whisk together the flour and milk. Pour the mixture slowly into the soup pot, stirring constantly. Increase the heat to medium high and continue to stir until the soup thickens, about 5 minutes. Remove from heat. Season with lemon zest and cracked black pepper to taste. Serve in warmed bowls.

• 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 (whole-meal) flour
• 1 1/2 cups fat-free milk
• Lemon zest, to taste
• Cracked black pepper, to taste