Begin by placing the halved baby potatoes in a large pot and covering them with cold water, adding a generous pinch of salt. Bring the water to a rolling boil over high heat, then reduce to a simmer for 10-12 minutes until the potatoes are fork-tender. Drain the potatoes and let them cool in a colander while you prepare the other ingredients.

In a mixing bowl, whisk together the Greek yogurt, mayonnaise, fresh lemon juice, Dijon mustard, minced garlic, salt, and pepper until well combined and creamy. If the dressing is too thick for your liking, gradually add 1-2 tablespoons of water, whisking until you reach the desired consistency.

In a large serving bowl, gently combine the cooled potatoes, thinly sliced cucumber, and red onion. Pour the creamy dill dressing over the mixture and carefully toss to coat all the ingredients evenly without breaking the potatoes.

Cover the salad with plastic wrap or a lid and refrigerate for at least 30 minutes to allow the flavors to meld.

After chilling, give the salad a gentle stir to redistribute the dressing. Taste and adjust seasoning with additional salt, pepper, or lemon juice if needed.