Place the raw chicken in the bottom of the slow cooker in a single layer if possible.
In a bowl, whisk together the soy sauce, hoisin sauce, Thai sweet chili sauce, balsamic glaze, honey, minced garlic, and diced onion until smooth.
Pour the sauce mixture evenly over the chicken in the slow cooker.
Cover and cook on low for 4 to 5 hours, until the chicken is very tender and easily shreds with forks.
Transfer the cooked chicken to a cutting board and shred with two forks into thin strips; return some sauce from the slow cooker to the shredded chicken to keep it moist.
While the chicken cooks, make the slaw: combine shredded Napa cabbage, shredded red cabbage, shredded carrots, thinly sliced red bell pepper, rice vinegar, and sugar in a large bowl; toss to combine and refrigerate until ready to use.
Divide the shredded chicken among the slider buns, top with slaw and fresh cilantro, and drizzle with Sriracha and sprinkle sesame seeds if desired; serve immediately.
