Preheat the oven to 425°F. Add 3 tablespoons of the melted butter to a 10-inch cast-iron skillet. Add one-third of the potato slices in a circular pattern, overlapping them slightly. Brush with 2 tablespoons of the butter and sprinkle with ½ teaspoon of the salt.

Make two more layers with the remaining potatoes, butter, and salt, piling any remaining potatoes in the center (this will create an even pommes Anna after everything is cooked). Set over medium heat and cook, without moving the pan, for 10 minutes.

Butter one side of a piece of aluminum foil and cover the pan, buttered-side down. Use a 9-inch cake pan to press down firmly on the potatoes. Remove the cake pan and place the skillet in the oven for 20 minutes. Remove the skillet and again use the cake pan to press the potatoes down firmly. Remove the foil and continue to bake until the potatoes are tender and the top is deeply browned, about 30 minutes more.

Let rest for 10 minutes, either then run a thin spatula around the edges and bottom of the skillet and flip it carefully onto a serving platter so the golden bottom faces up or, if you’re not feeling lucky, simply serve warm in the pan as is. Top with smoked salmon, pickled shallots and radishes, dill, chives, and freshly ground black pepper.

In a small saucepan, combine ⅓ cup red wine vinegar, ⅓ cup water, 1½ teaspoons granulated sugar, 1½ teaspoons fine sea salt, 6 to 8 whole black peppercorns, and 1 bay leaf. Bring to a simmer and cook until the sugar dissolves. Thinly slice 4 to 5 medium shallots and 4 to 6 small radishes and add to a small heatproof bowl or jar and pour the vinegar mixture on top. Cover and refrigerate for at least 2 hours before using. Shallots can be made up to a week ahead.