Put potatoes in a large pot and cover with water. Add a little salt and bring to boil. Cook about 8-10 minutes until tender. Drain potatoes and then chill.
Meanwhile put cucumber in bowl. Add yogurt, mayonnaise, parsley, dill, lemon juice, garlic and season with salt and pepper. Add in potatoes and red onion and evenly coat. Garnish with parsley, dill and lemon zest.