Fried Fingerling Potatoes with Tarragon Sauce

Preparation

1. Step 1

   Bring potatoes, 1/4 cup kosher salt, and 8 cups water to a boil in a large saucepan and cook until potatoes are tender, about 12 minutes. Drain; let cool completely. Halve potatoes lengthwise. DO AHEAD: Can be made 1 day ahead. Cover and chill.

   Step 2

   Whisk egg yolk, lemon juice, and a pinch of sea salt in a small bowl. Gradually whisk in 1/2 cup olive oil until mayonnaise forms. Stir in shallot and tarragon. Season to taste with pepper. DO AHEAD: Can be made 4 hours ahead. Cover and chill.

   Step 3

   Heat remaining 1 1/2 teaspoons olive oil in a small skillet over medium-high heat. Add capers and fry, stirring often, until crisp and golden, 2-3 minutes. Using a slotted spoon, transfer capers to paper towels to drain. DO AHEAD: Can be made 4 hours ahead. Let stand at room temperature.

   Step 4

   Pour vegetable oil into a large pot to a depth of 2". Attach a deep-fry thermometer to side of pot. Heat oil over medium heat until thermometer registers 375°F. Working in batches, fry potatoes until crisp and dark golden brown, 3-4 minutes. Drain on paper towels. Season lightly with sea salt.

   Step 5

   Arrange warm potatoes on a platter, cut side up. Spoon some mayonnaise over each; sprinkle with capers.