Begin by trimming the chicken breasts so they're an even thickness. This makes sure they cook uniformly. If you have any scraps, consider saving them for homemade chicken stock!
Next, cut the chicken breasts lengthwise into about 4 strips. Then, cut those strips again lengthwise and finally crosswise until you have thin strips of chicken that are about the same length as your pepper strips will be.
In a bowl, mix the lime juice, olive oil, taco seasoning, and a bit of salt to create a marinade that will infuse the chicken with flavor.
Place the chicken strips into a Ziploc bag, adding slightly over half of the marinade. Seal the bag, ensuring all the chicken is coated, and marinate in the fridge for 4 to 8 hours, or as long as you can manage. The longer, the better!
When ready to cook, preheat your oven to 425F/220C. Put the sheet pan inside while it heats up, so it’s hot when you add the chicken.
While the oven heats, cut the bell peppers and onion into strips. Toss them with the remaining marinade to coat them in flavor.
Now, arrange the marinated chicken on the hot sheet pan. This ensures a nice sear, which gives the dish great flavor. Bake for 8 minutes.
After 8 minutes, remove the sheet pan from the oven. At this point, some chicken may release water while baking. If this happens, simply tip the pan slightly to drain off excess water or blot it with paper towels.
Next, tuck the strips of pepper and onion between the chicken pieces, aiming to have everything in a single layer for even cooking.
Put the sheet pan back into the oven and bake for about 15 more minutes, or until the chicken reaches an internal temperature close to 165F/75C and the peppers are tender to your liking. If you’re planning to broil for a bit more browning, you may want to reduce this cooking time slightly.