Preheat the oven to 425℉.

Place the quartered potatoes on a greased or parchment paper-lined baking sheet and roast them for 35-40 minutes, or until golden brown with tender, fluffy insides.

Meanwhile, in a large mixing bowl, combine the onions, cucumber, pistachios, dill, and parsley. Mix and set aside.

In another bowl, combine the mayo, mustard, garlic, lemon, sweetener, salt, pepper, and red chili flakes (if using). Whisk until smooth.

Once the potatoes are roasted, let them cool for a few minutes.

Toss the potatoes with the dressing, then pour the chopped veggies over the salad. Gently mix until all is well combined.

Serve right away for a warm potato salad or chill in the refrigerator for a cold potato salad.