Mashed Potato Soup With Wasabi and Chives Recipe

January 23, 2014 Updated: January 17, 2014

Mashed Potato Soup With Wasabi and Chives

Courtesy of chef Masaharu Morimoto 
Morimoto, NYC

1 large baking potato, such as Idaho or russet (10 to 12 ounces)
1 1/2 sticks (6 ounces) unsalted butter
3/4 cup half-and-half
4 cups dash (see below)
2 tablespoons sake
3 tablespoons light-colored soy sauce
1 ounce caviar, optional
Freshly grated wasabi and finely sliced chives, preferably baby chives (menegi), for garnish

1. Prick the potato in a couple of places. Steam over boiling water until the potato is tender when pierced with the tip of a sharp knife, 30 to 35 minutes. Let cool, then peel off the skin. Press the potato through a ricer or a wire sieve set over a medium saucepan, scraping with a rubber spatula to pass it all through.

2. In a small saucepan, combine the butter and half-and-half. Warm over medium heat until the butter melts and the liquid is steaming but not simmering. (Can also use leftover mashed potatoes.)

3. Place the saucepan of mashed potatoes over low heat. Slowly whisk in the hot butter and half-and-half until the potatoes are thick and smooth. Remove from the heat and cover to keep warm.

4. Quickly bring the dash, sake, and soy sauce to a boil over high heat. Spoon equal amounts of the mashed potatoes into 4 soup bowls. Gently ladle the hot dash over and around the potatoes. Top with a spoonful of caviar if you have it. Garnish with the grated wasabi and chives. Serve immediately.


(Makes 1 liter)

1 piece of dashi kombu, 4 x 6 inches 
4 cups filtered spring water
1/2 cup loosely packed bonito flakes

1. The night before using the dashi, wipe the kombu clean with a wet kitchen towel to remove any grit, but do not rub off the white powder; much of the flavor lies in its natural MSG. Place in a medium saucepan and add the spring water. Let stand at room temperature overnight.

2. The next day, remove the kombu and bring the water to a simmer over medium heat. When it reaches a boil, remove from heat and add the bonito flakes. Let stand until the bonito flakes sink to the bottom of the saucepan, about 15 minutes.

3. Line a wire sieve with moistened, squeezed dry cheesecloth and place over a bowl. Strain the dashi through the sieve. Use the dashi within a couple hours of making.