Begin by dicing the russet potatoes into approximately ½-inch cubes. Once prepared, place them in a pot of boiling water. Allow them to boil for roughly 12-15 minutes or until they approach a fork-tender consistency.

Following this, introduce the frozen peas into the pot and continue boiling for an additional 3-5 minutes. Once the potatoes and peas are adequately boiled, drain the water and set them aside in a separate dish.

In a clean saucepan, melt the unsalted butter over a medium flame. Subsequently, incorporate the finely diced onions. Sauté the onions until they attain a translucent appearance.

Pour the heavy cream into the saucepan containing the onions. Allow this mixture to come to a slight boil. Monitor the cream closely; once it begins to thicken, promptly remove the saucepan from the heat.

Carefully combine the boiled potatoes and peas into the creamed mixture in the saucepan. Finish by seasoning the dish with dried dill, salt, and pepper. Ensure all ingredients are well-integrated before serving.