1) Put the potatoes in a medium saucepan and just cover with cold water. Add 2 teaspoons of the salt and stir. Over high heat, warm to a simmer. Reduce heat to low. Stir and then partially cover the pot. Simmer the potatoes until the are fork tender, 5-8 minutes.
2) Meanwhile, in a large skillet melt the butter over medium-low heat. Add the onion and cook, stirring occasionally, until translucent, 3-5 minutes.
3) Add the whipping cream and remaining 1/4 teaspoon of salt and the pepper. Stir. Increase the heat to medium and bring the cream up to a boil, stirring constantly. Reduce the heat to low and add the dill.
4) Drain the potatoes and add them to the skillet, using a spoon to turn them over in the cream sauce.