In a bowl, whisk together the sugar, sriracha and butter. Place in the microwave for 20 seconds, then remove and whisk well to combine. Drizzle the mixture over the popcorn in layers – I like to drizzle, then toss well, drizzle, then toss well, until all the sriracha is used and the popcorn is coated. Sprinkle the sesame seeds on and drizzle the toasted sesame oil with one more toss. Serve!