To make the dressing, combine the peanut butter, vinegar, sesame oil, and sriracha sauce in a medium skillet over medium heat. Season with salt and black pepper, to taste, and heat, stirring continually, until the peanut butter melts and the ingredients are thoroughly combined, approximately 2-3 minutes.
Reduce heat to low and whisk in remaining dressing ingredients until combined. Simmer, stirring occasionally, until heated through, approximately 2 minutes. Remove from heat and set aside. Keep warm.
Combine shredded green cabbage, red cabbage, carrots, bell pepper, green onion, and fresh cilantro in a large bowl. Season with salt and black pepper, to taste, and drizzle with a small amount of the warm peanut dressing. Toss to combine.
Transfer salad to a decorative serving platter and top with chopped peanuts, Mandarin oranges, and sesame seeds. Serve immediately with remaining peanut dressing on the side.