Place potatoes in a large pot then add enough water to cover and season water with a teaspoon of salt.Bring to a boil over medium-high heat then cover and reduce heat to medium-low and let simmer until potatoes are fully tender, about 8 - 10 minutes.Drain potatoes, then chill fully (to chill faster spread onto a rimmed baking sheet and freeze for about 10 - 15 minutes).Meanwhile place diced cucumber on a few layers of paper towels and wrap and press to remove some of the excess liquid.Transfer cucumber to a large mixing bowl, add in Greek yogurt, mayonnaise, parsley, dill, lemon juice, and garlic then season with salt and pepper to taste. Stir mixture.Add potatoes and red onion to bowl then toss to evenly coat. Serve within a few hours garnished with more parsley, dill and lemon zest (keep chilled).Recipe source: Cooking Classy