Tangy cucumber salad

Going through my refrigerator yesterday, I discovered an English cucumber I'd forgotten about. Voila! Cucumber salad.

From inspiredtaste.net:

2 hot house or seedless cucumbers (about 1 1/2 pounds)
Kosher salt
2 to 3 teaspoons granulated sugar, depending on how sweet you like the salad
1/4 cup (60 ml) cider vinegar, or distilled white vinegar
2 teaspoons Dijon-style mustard
1 medium red onion, thinly sliced (optional)

Slice cucumbers into 1/16-inch (1.5 mm) slices, toss with 2 teaspoons of salt then add to a colander. Drain for 30 minutes. Rinse cucumbers then squeeze excess water from them. In a large bowl, whisk together 2 teaspoons of sugar, vinegar and mustard. Taste then add the additional teaspoon of sugar if needed. Add cucumbers and red onion then toss. Refrigerate salad at least 1 hour and up to a day before serving.