Twice-fried potatoes with a golden brown crust

Ingredients:

• 3 large Russet Burbank potatoes, with skins
• 3 tablespoons Dijon mustard
• 1/4 cup sherry vinegar
• 1/3 cup olive or peanut oil, or shortening, for frying
• 0.5 cup thinly sliced ​​green onions
• Flaked sea salt

Preparation:

1. Preheat the oven to 200°C (400°F). Brush the potatoes, place them on a baking sheet, and bake until the thickest part is easily pierced with a knife, about 1 hour and 15 minutes. Remove the baking sheet from the oven and let the potatoes cool completely. Break the potatoes into rough 2-5 cm pieces by hand. The potatoes can be baked up to 1 day in advance and refrigerated.
2. In a small bowl, combine the mustard and vinegar. Whisking constantly, add the olive oil to create an emulsified dressing.
3. In a deep fryer or large saucepan, heat about 4 inches of vegetable oil or shortening over medium heat to 350°F (180°C). Fry the potatoes in batches until golden brown and crispy, stirring frequently with a slotted spoon, about 4 minutes. When the potatoes are done, transfer them to a paper towel-lined plate with a slotted spoon.
4. In a large bowl, combine the potatoes, onions, and enough vinaigrette to lightly coat the vegetables (about 2 tablespoons). Toss to distribute evenly. Transfer to a serving platter, sprinkle with salt, and serve.