Saute onions in Olive oil on medium high heat until they start to soften
Add in Bell Peppers, reduce heat to medium low and cover for 5-8 minutes to allow them to sweat and soften.
Remove the lid and allow to cook uncovered until it starts to dry. If it get's to dry, de-glaze the pan with a little bit of water (1-2 TBSP).
Return heat to medium high, add in the chicken and allow to cook 3-5 minutes or until done.
Add the taco seasoning mix, stir it in to coat everything evenly, cover and let sit for 5 minutes. Serve with warm tortillas or on a bed of white rice.