Ingredients

• 1/2 cup mashed potatoes (optional)
• 1/2 cup sour cream
• 1 tablespoon finely grated peeled fresh horseradish
• 1 teaspoon chopped fresh dill
• 1 teaspoon chopped fresh flat-leaf parsley
• 1 teaspoon fresh lemon juice
• Kosher salt, ground pepper
• 4 slices Danish rye or pumpernickel bread
• 8 ounces sliced smoked salmon
• 2 radishes, thinly sliced
• 2 tablespoons salmon or trout roe (optional)
• Dill sprigs and flat-leaf parsley leaves
• Kosher salt, ground pepper

Instructions

1. Whisk potatoes, if using, sour cream, horseradish, dill, parsley, and lemon juice in a small bowl; season with salt and pepper.
2. For assembly: Spread horseradish sour cream on bread and top with smoked salmon, radishes, roe, if using, dill, and parsley. Season with pepper.
3. Spread horseradish sour cream on bread and top with smoked salmon, radishes, roe, if using, dill, and parsley. Season with pepper.