Start by preheating your oven to 425°F (220°C) and lining a baking sheet with parchment. Boil the baby potatoes for about 7 minutes until fork-tender. This ensures the inside stays soft while roasting.
Once boiled, drain the potatoes and transfer them to the baking sheet. Use a glass or masher to gently flatten them, then brush with olive oil and sprinkle with salt and pepper. Roast for 50 minutes to 1 hour until golden and crispy, flipping halfway if needed.
While the potatoes roast, mix Greek yogurt, mayonnaise, Dijon mustard, lemon juice, red wine vinegar, minced garlic, dill, parsley, salt, and pepper in a bowl. Fold in the cucumber and shallot, then refrigerate to let the flavors meld.
Let the roasted potatoes cool for 5 minutes, then gently fold them into the chilled dressing. Garnish with reserved crispy potato bits, extra dill, and freshly cracked black pepper. Serve immediately or chill for later.