Preheat oven to 425 degrees Fahrenheit.
Line a large baking sheet with parchment paper.
In a small bowl make the sauce, add chili powder, cumin powder, oregano, salt, minced garlic cloves, avocado oil, and lime juice. Set aside.
Thinly slice all bell peppers and onion. I aim for 1/8-1/4 inch. It's important to slice everything as evenly and thinly as possible to ensure they cook quickly and evenly.
Add chicken tenders and sliced veggies to a large sheet pan.
Pour the sauce over the chicken tenders, bell peppers, and onions, using your hands or tongs to evenly coat. Be sure everything is in an even layer.
Cook for about 22 minutes, or until the chicken is fully cook and reaches a temperature of 165 degrees Fahrenheit. For the best results, place the chicken on a separate plate and cover with foil while the veggies roast to your desired doneness.