Potato Soup with Gravlax Rosettes

1 tablespoon butter

3 russet potatoes, peeled and finely diced

1 onion, chopped

2 cups vegetable broth

6 tablespoons mascarpone cheese

salt and black pepper to taste

½ teaspoon lemon juice, or to taste

4 (1 ounce) slices thinly sliced smoked salmon (gravlax)

2 tablespoons mascarpone cheese

1 tablespoon chopped fresh chives

Melt butter in a saucepan over low heat, and cook and stir the potatoes and onion until the onion starts to become translucent, about 3 minutes. Raise heat to medium, pour in the vegetable broth, and bring to a boil. Reduce heat to a simmer, cover, and cook until the potatoes are tender, 10 to 15 minutes. Pour the mixture into a large bowl, and puree through a food mill back into the saucepan. (Discard any fibrous vegetables left in the food mill.)

Bring the pureed soup back to a simmer over medium-low heat, and whisk in 6 tablespoons of mascarpone. Season with salt, pepper, and lemon juice to taste.

Preheat oven to 200 degrees F (95 degrees C), and warm 4 oven-safe soup plates for about 5 minutes.

Roll a slice of smoked salmon loosely into a rose shape, pinching the roll at the bottom and fanning the roll out at the top. Place a rosette of salmon into the bottom of each warmed soup plate, gently pour the soup over the rosette, and drizzle each bowl with about 1/2 tablespoon of mascarpone cheese. Sprinkle with chives, and serve.