Combine the Greek yogurt, cilantro, lime juice, cumin, salt, black pepper, green onions, garlic and jalapeño (if using) in a blender or food processor. Pulse briefly a few times until the mixtures is combined.
Place the cole slaw mix in a large mixing bowl. Drizzle the sauce on top of the cole slaw, then toss until the mixture is evenly combined. Season with extra pepper and/or lime juice if needed.
Serve immediately, or cover and refrigerate for up to 24 hours.
