Slice the cucumber into ⅛-inch thick slices using a mandolin or a sharp knife.
Place the sliced cucumber into a large deli container or glass jar. Add in the diced crab, diced avocado, mayo, cream cheese, soy sauce, and sesame seeds.
Cover the container or jar with a lid securely. Shake vigorously until all the ingredients are well combined and evenly distributed.
Eat the mixed salad immediately for the freshest taste, or serve it in a bowl for a more formal presentation. Garnish with additional sesame seeds if desired.