Add the sesame seeds to a large skillet and set over medium heat. Toast, tossing frequently, until deeply golden brown, about 3 to 4 minutes. Immediately transfer to a blender or food processor and blend until sandy in texture. There should still be some whole seeds present in the mixture.
In a medium bowl combine the crushed seeds, mayo, rice vinegar, tahini, soy sauce, sesame oil and sugar. Whisk until fully combined, then set aside.
Add the cabbage to a very large bowl and sprinkle over with your desired amount of furikake and dressing. Toss thoroughly until the cabbage is fully coated, transfer to a platter, top with more furikake and serve.
