Heat the olive oil in a large skillet over medium heat.
Add the chopped chicken and brown on all sides, about 8 minutes; transfer chicken to a plate and set aside.
Add the broccoli florets to the skillet and sauté briefly until slightly tender, about 2–3 minutes; remove and set aside.
Add the chopped onion and sliced celery to the skillet and cook 5–8 minutes until the celery softens and the onion becomes translucent.
Stir in the minced garlic and cook about 30 seconds until fragrant.
Return the chicken and broccoli to the skillet, add the chicken broth or water, and season with salt and pepper; cook about 5 minutes until heated through.
Whisk together the coconut aminos (or tamari/soy) and vegetable Sriracha, then pour the sauce into the skillet during the last minute of cooking and stir to coat.
Remove from heat and serve immediately.
