Mini Hasselback Potatoes

Place a rack in lower third of oven; preheat to 425°. Place 1 baby Yukon Gold, peewee, or new potato, scrubbed, on a cutting board so a long side is facing you and arrange a chopstick or the handle of a wooden spoon along each long side. Using a long knife, cut potato crosswise into ⅛"-thick slices, stopping at chopsticks (about ¼" before you cut all the way through). Transfer to a large bowl. Repeat with remaining potatoes.

Drizzle cut hasselback potatoes with ⅓ cup extra-virgin olive oil and sprinkle with 1 Tbsp. plus 1 tsp. Diamond Crystal or 2¼ tsp. Morton kosher salt and 1 tsp. freshly ground black pepper. Gently massage oil all over potatoes, making sure to work some into slits. Arrange potatoes, cut side up, on a parchment-lined rimmed baking sheet, spacing at least 1" apart. Cover tightly with foil and bake potatoes until just barely tender, 20–25 minutes. Remove foil and continue to bake until tops of potatoes are golden brown and crisp, 40–45 minutes more.

Stir together 2 garlic cloves, finely grated, and remaining 3 Tbsp. extra-virgin olive oil in a small bowl, then brush over hot potatoes.

Stir 1 cup sour cream, ⅓ cup mayonnaise, 2 Tbsp. finely chopped chives, 2 tsp. onion powder, 2 tsp. Worcestershire sauce, 1 tsp. fresh lemon juice, 1 garlic clove, finely grated, ¾ tsp. Diamond Crystal or ½ tsp. Morton kosher salt, and ½ tsp. freshly ground black pepper in a medium bowl to combine. Taste and season with more salt and/or pepper if needed.

Spread sour cream mixture over a platter; arrange potatoes, cut sides up, on top. Scatter thinly sliced chives over, then sprinkle with flaky sea salt and more pepper.