Preheat oven to 450℉
Marinate the chicken: In a medium bowl, add the chicken and mix in olive oil, smoked paprika, chili powder, cumin, garlic powder, oregano, salt, pepper, and lime zest. Let this sit while you slice the peppers and onions; or, marinate the chicken ahead of time for several hours or overnight.
Slice the peppers and onions into 1/2 inch slices. If adding jalapenos, cut into pepper carefully along the long side and cut away the seeds (the seeds are what is spiciest!).
Arrange the marinated chicken on one side of a foil-lined sheet pan. Lay the peppers and onions on the other side.
Crease the foil in the middle of the pan so that there is a separation from the chicken and peppers to keep the chicken juices in place. (Too much moisture with the veggies will prevent them from browning).
Place the pan in the oven and cook for 15 minutes. Check the chicken to make sure it is done (internal temperature should be 165 degrees F). Remove chicken when done. If you want the peppers to char more, you can leave them in and set the oven to broil for 3-5 minutes.
Serve with warm tortillas, avocado or guacamole, sour cream or plain Greek yogurt, lime wedges, fresh cilantro, and salsa.