INGREDIENTS
potatoES
4 1/2 lbs kosher salt
10 large yukon gold potatoes , scrubbed (about 4 1/2 pounds)
6 scallions , white and light green parts thinly sliced, dark green parts cut into 1-inch lengths
1 1/2 cups unsalted butter , softened (3/4 lb)
table salt & freshly ground black pepper
2 tablespoons grainy mustard
1 1/2 teaspoons Dijon mustard
1 1/2 tablespoons drained prepared horseradish
1 tablespoon fresh lemon juice (Please not the bottled stuff!)

DIRECTIONS

Preheat the oven to 400°F
Spread a layer of kosher salt 1/2 inch thick [...]