1/4 cup plus 1 teaspoon kosher salt, divided, plus more for serving
Canola oil (for frying)
2 tablespoons yellow mustard seeds, divided
1 cup all-purpose flour
3 tablespoons cornstarch
2 tablespoons Hungarian sweet paprika, plus more for serving
1/2 teaspoon freshly ground black pepper, plus more for serving
1/4 teaspoon garlic powder, plus more for serving
2 cups buttermilk
A deep-fry thermometer
Directions
Combine potatoes, 1/4 cup salt, and 3 qt. cold water in a 5–7-qt. pot. Bring to a boil, then reduce to a simmer; cook until just fork-tender, 2–3 minutes. Drain, arrange in a single layer on a large plate, and chill until cold, about 20 minutes (handle potatoes delicately; they will be fragile until chilled).
Pour oil into a wide heavy pot to a depth of 2". Heat over medium-high until deep-fry thermometer registers 350°F.
Meanwhile, coarsely crush 1 Tbsp. mustard seeds. Combine flour, cornstarch, 2 Tbsp. paprika, 1/2 tsp. pepper, 1/4 tsp. garlic powder, 1 tsp. salt, crushed mustard seeds, and remaining whole mustard seeds in a large bowl. Combine buttermilk and chilled potatoes in another large bowl. Dredge potatoes in flour mixture, then transfer to a plate as you go.
Working in two batches, fry wedges, turning once halfway through, until crisp, 6–8 minutes per batch. Drain on paper towels. Transfer to a serving platter, then season with salt, pepper, paprika, and garlic powder.
