Place potatoes in a large pot and cover with water. Add 1 tablespoon salt and bring to a boil over high heat. Reduce heat to medium-high and cook until fork tender, about 12 to 15 minutes; drain.

Preheat the oven to 425°F (220°C).

Line a rimmed baking sheet with parchment or foil and coat with 1 tablespoon of olive oil. Add the potatoes in a single layer onto the pan. Using a heavy bottomed jar or glass, smash the potatoes 1/2-inch thick, taking care not to fully separate the potatoes. Drizzle smashed potatoes evenly with remaining 1 tablespoon oil and sprinkle with remaining 1 teaspoon salt and pepper.

Roast the potatoes in the preheated oven, flipping halfway through cooking time, until very crispy and browned, about 40 to 50 minutes.

Meanwhile, prepare the dressing. Combine honey, whole grain mustard, yellow mustard, mayonnaise, and apple cider vinegar in a large bowl and whisk until well blended.