In my family, before other people's traditions overtook ours, we always had a cucumber salad. It can be made very Asian or very European (done it both ways). First very thinly slice cucumbers. As is the case here, if you cannot get ones with small seeds, then seed them. Very easy to do with a grapefruit spoon. You'll need a cuke for every 3 people.
a can of sliced mushrooms, drained
2/3 c vegetable oil
1/4 c vinegar (I prefer something sweet like rice or malt, but in the old days mom made it with plain old distilled)
1/2 tsp salt
1/2 tsp coarse ground pepper
1/4 c sugar
If you wish to use fresh mushrooms (were not readily available when I was a kid, and very $$$ in those days), slice them thinly then soak in the dressing overnight. they will absorb a lot, so you may need to double the dressing.
We always had shrimp in this salad, even if it was canned and a real luxury. If you put shrimp in it, you can easily serve the salad as a first course. If serving it as a side salad, I allow only a shrimp or two per person because you don't want it too rich.
To make it very eastern European, add a half teaspoon dried dill (for most of us it is too late in the year for fresh, but double it for fresh).
To make it more Asian, add a dash of sesame oil or a 1/2 tsp sesame seeds (preferably toasted) and a bit of ginger.