Add the chicken to a slow cooker. Pour teriyaki sauce to the one-cup mark on a liquid measuring cup. Add a tablespoon of sriracha to the teriyaki sauce and stir to combine, then pour it all over the chicken.
Cook on low for 3 hours, then shred the chicken into large chunks with two forks. Add the broccoli and if needed, 1/2 cup of additional teriyaki sauce. Stir to combine. Put lid back on slow cooker and continue cooking on low for another 30 minutes to an hour, or until a meat thermometer reads the internal temperature of the chicken to be 165°.
Garnish the teriyaki chicken & broccoli with sliced scallions and toasted sesame seeds and serve over your rice or your favorite side. Enjoy!
Notes
For the best texture, fresh broccoli is recommended.