In a large mixing bowl, combine the grated butternut squash, shredded cabbage, grated carrot, julienned green pepper, and raisins.
Toss gently to distribute everything evenly.
In a separate small bowl, whisk together the mayonnaise, plain yogurt, sugar, vinegar, salt, and a few grinds of black pepper until smooth.
Pour the dressing over the vegetable mixture and toss thoroughly until everything is well-coated.
Cover the bowl and refrigerate for at least 1 hour to allow the flavors to meld together before serving.