We serve this salad on whole-grain toast as an open-face sandwich, but it is also delicious mounded on a bed of crisp salad greens.
Sprinkle cucumber lightly with salt, and place in a fine sieve set over a medium bowl. Cover with plastic wrap, and place in refrigerator 30 minutes. Rinse and drain well; discarding liquid.
Combine crabmeat, corn, onion, avocado, cucumber, and 1/2 cup cucumber vinaigrette in a large bowl, and stir to combine. Season with salt and pepper. Store in an airtight container in refrigerator until ready to serve.