Heat 2 tablespoons oil in a large pan over medium high heat. Add the onions and bell peppers along with a pinch of salt and cook until lightly browned, 5-10 minutes. Set aside and do not clean pan.
Add remaining 2 tablespoons oil to the now empty pan over medium high heat. Add chicken and sauté until browned, about 5-10 minutes.
While chicken browns, stir together monk fruit, vinegar, gluten free soy sauce, tomato paste, sriracha, and broth. Set aside
Add the garlic and ginger to the chicken and cook until fragrant, another minute. Add the sauce mixture and cook until reduced by half, another 5-10 minutes.
Off heat, add sesame oil, taste and adjust salt, sweetener, and vinegar to taste. Add back sautéed vegetables and garnish with green onions and sesame seeds, if using.