Preheat the oven to 375 F and line a rimmed baking sheet with aluminum foil.
Place the potatoes on the prepared baking sheet and toss with 2 tablespoons of the olive oil to coat. Place on the middle rack in the oven and roast for 40 minutes. When the potatoes are fork-tender and crispy on the outside, remove from the oven and set aside to cool slightly.
While the potatoes are roasting, make the dressing: Whisk together the mayonnaise, mustard, curry powder, Tamari soy sauce or Bragg Liquid Aminos, and caraway or fennel seeds, if using, in a large bowl until well combined.
Add the slightly cooled potatoes to the bowl and toss well to coat with the dressing. Add the apple and kale, and gently toss again and serve immediately!