Place potatoes in a large pot and cover with cold, salted water by 2 inches. Bring to a boil over high heat, then reduce to medium-high and cook for 15-20 minutes until fork-tender but not falling apart.

Preheat your oven to 425°F and line a large baking sheet with parchment paper. Drain the potatoes thoroughly and let them cool for 5 minutes until comfortable to handle. Pat them dry with paper towels to remove excess moisture.

Using a potato masher, fork, or the bottom of a glass, gently press down on each potato until it flattens to about ½-inch thick. Drizzle with olive oil and sprinkle with salt and pepper, ensuring every crevice gets seasoned.

Roast for 25-30 minutes until the edges turn golden brown and crispy. The potatoes should develop beautiful golden-brown patches while maintaining creamy centers.

While potatoes roast, whisk together mayonnaise, Dijon mustard, apple cider vinegar, garlic powder, green onions, and dill in a large bowl.

Transfer warm roasted potatoes to the bowl with dressing and gently fold together, being careful not to break up the crispy edges completely. Taste and adjust seasoning as needed.