Start by chopping the chicken breast into bite-sized pieces. In a bowl, toss the chicken with the almond or coconut flour until well coated.
In a large skillet or wok, heat the tablespoon of oil over medium-high heat until shimmering.
Add the coated chicken pieces to the skillet and cook for about 5-7 minutes until golden brown and cooked through. Remove and set aside.
In the same skillet, add more oil if necessary, then add minced garlic and ginger. Cook for about 30 seconds until fragrant, then add chopped onion and cook until translucent.
Add chopped broccoli and bell pepper to the skillet. Stir-fry for about 5 minutes until tender-crisp.
Return the cooked chicken to the skillet, mix with the vegetables, and pour in the keto stir fry sauce. Toss everything together for an additional 2-3 minutes.
Drizzle sesame oil over the stir fry and add chili sauce if desired. Mix well.
Serve hot, garnished with sesame seeds or chopped green onions if desired.