Toss cucumber with salt in large bowl. Cover with plate that rests directly on cucumbers; weight down with 1-pound can. Let stand 1 to 2 hours. Drain in colander; rinse well.
Combine lemon juice, oil, sugar, and dill in serving bowl. Mix in onion and cucumber. Refrigerate overnight. Serve cold or at room temperature.
If you are concerned if the oils or other ingredients in these recipes are suitable for Passover, seek non-dairy substitutes or ingredients that are certified kosher for Passover.