Sriracha is a Thai hot sauce made of chili peppers, distilled vinegar, garlic, sugar, and salt, and comes in at 2,000 scoville units, or less than half that of jalapeño peppers--according to Wikipedia! I love not only the heat, but the flavor it provides to this dish. My kids find the 2 teaspoons called for in this recipe to be not overly spicy, yet there is a bit of a kick. Feel free to start with one teaspoon if you are unsure, or ramp it up a little higher if you really love the extra heat. You can find this in the Asian or international foods aisle of most larger grocery stores.
Combine all the ingredients except for the chicken. (To incorporate the peanut butter better, I find it helpful to warm for about 15-20 seconds in the microwave, especially if using natural peanut butter that has been stored in the refrigerator.) Place the chicken in a bowl, add the chicken, and toss to thoroughly coat. Although I often marinate meat in a zipper top bag, I use a bowl for this recipe as I want to be able to easily scrape all the marinade into a saucepan later. Marinate chicken, ideally for a minimum of 3-4 hours or up to all day.
Heat a large skillet or saucepan over medium heat. Add the chicken and all of the sauce. Cook, stirring occasionally, for 7-8 minutes or until chicken is just cooked through.
Sprinkle with sesame seeds and cilantro, if desired.