Mix the taco seasoning into the chicken with a fork, and let it rest while you get the vegetables ready.
Slice all veggies to be of equal size, lengthwise.
Line a baking pan with foil and place the veggies on the foil.
Pour oil, sprinkle the salt and pepper over them, and use your hands to mix everything well.
Push the vegetables to the side and place the seasoned chicken in the middle. You want to do this because the chicken actually cooks faster than the vegetables and you want to be able to pull it out when it's done.
Place the pan in the oven for 15 minutes until the chicken is almost cooked through.
Move the pan to the top rack, turn on the broiler to hot and set the timer for 5 minutes. Take out the chicken after five minutes and let the rest of the vegetables broil until the edges are charred and the onions are soft.
Serve with low carb tortillas or just enjoy the chicken and veggies by themselves.