1. Place eggs in a single layer in a large saucepan. Add cold water to cover eggs by 1 inch. Bring to a boil over high heat. Turn off heat, cover pot and let stand for about 10 minutes. Drain and cover with cold water to stop cooking. When eggs are cool, peel. Cut into 1/2-inch dice.
2. In a large bowl, whisk mayonnaise and mustard until thoroughly combined. Using a rubber spatula, gently fold in eggs, beets, gherkins and chopped dill; mix well. Season with salt and pepper. Cover and refrigerate until well chilled--at least 2 hours--before serving. Garnish with dill sprigs, if desired.