Oyster sauce, made from oysters, is a common umami seasoning. Oyster sauce has high nutritional value and good taste. If you like, you can add some to the salad to add flavor.
But when making cold salad, it is not appropriate to put oyster sauce directly, it will be sticky and taste bad.
It is best to pour hot oil on oyster sauce, then add other seasonings, stir well, and finally move into cold dishes.