In the water kettle, bring water to boil. Pour into the pot just until the water touches the bottom of the steamer basket.
Place the potatoes in the steamer basket in a single layer. Cover and steam for 15 to 20 minutes, or until they are tender. You can test with a bamboo skewer. Potatoes should be cooked all the way through, but not mushy. Remove potatoes from the pot and allow to cool to room temperature.
Cook the Eggs
While the potatoes cook, place eggs in the 2-quart saucepan, cover with 1 inch of water, and bring to boil over high heat. Remove the pan from heat, cover, and let sit for 10 minutes. Just before the eggs finish the sitting time, add ½ cup of ice and 1 cup of cold water to the medium bowl. Transfer the eggs to ice water bath with slotted spoon and allow to sit 5 minutes.
While the potatoes and eggs cool, stir together the mayonnaise, salt, and celery seed in a small bowl.
Peel the eggs. Cut the potatoes and eggs into small pieces and put into the large serving bowl. Stir in the onions and sauce until it is thoroughly distributed. Garnish with dill leaves and serve. Store covered in the refrigerator for up to two days.