Thinly slice the English cucumbers and sweet onions, then place cucumber slices in a colander. Sprinkle with salt and let sit for about 10 minutes to draw out moisture.

Rinse cucumbers to remove salt and pat dry with a paper towel.

Microwave cream cheese for 15 seconds until softened. In a mixing bowl, whisk together cream cheese, mayonnaise, soy sauce, rice vinegar, and sesame oil until smooth.

In a large bowl, combine drained cucumbers and sliced onions. Pour half the dressing over and toss gently. Let sit for 5 minutes, then add the remaining dressing and optional mix-ins, coating evenly.

Transfer salad to a serving bowl and garnish with sesame seeds or green onions. Serve immediately.