Wash the English cucumbers thoroughly. Using a sharp knife or a mandoline slicer, slice the cucumbers into very thin rounds. For English cucumbers, peeling is optional; the skin adds color and nutrients.

Place the sliced cucumbers in a colander. Sprinkle them generously with about 1 teaspoon of salt. Let them sit for 15-20 minutes over a sink or bowl. This step draws out excess water from the cucumbers, preventing the salad from becoming watery.

After 15-20 minutes, gently squeeze the cucumbers by hand or press them between layers of paper towels to remove as much liquid as possible. Pat them thoroughly dry. Set aside.

In a large mixing bowl, combine the plain Greek yogurt, finely chopped fresh dill, freshly squeezed lemon juice, white wine vinegar, minced garlic, granulated sugar, 1/2 teaspoon salt, and 1/4 teaspoon black pepper.

Whisk all the dressing ingredients together until smooth and well combined. Taste and adjust seasoning if needed, adding more salt, pepper, or sugar to your preference.

Add the patted dry cucumber slices and the thinly sliced red onion to the bowl with the creamy dill dressing. Gently toss everything until all the cucumbers and onions are evenly coated with the dressing.

Cover the bowl with plastic wrap and refrigerate for at least 30 minutes. This allows the flavors to meld beautifully and ensures the salad is nicely chilled.

Give the salad a gentle stir just before serving. Serve chilled as a refreshing side dish.