Thinly slice the fresh English cucumbers and place them in a medium glass bowl. Sprinkle with salt and toss gently to coat all slices. Let sit for 10 minutes at room temperature.

In a medium saucepan, combine water, distilled white vinegar, and sugar. Heat over medium-high heat, stirring until sugar fully dissolves (2-3 minutes). Remove from heat and let cool slightly.

Layer the thinly sliced onions over the salted cucumbers in the bowl. Pour the warm dressing over the vegetables, ensuring everything is evenly coated. Gently toss to combine.

Cover the bowl with plastic wrap and refrigerate for at least 20 minutes.

After chilling, give the salad a quick toss. Serve in a large bowl or on a platter, garnishing with fresh herbs or crumbled feta if desired.