Preheat your oven to 425 degrees F. This is important to ensure that the cooking process starts right and helps achieve that lovely roasted finish.
Line two rimmed baking sheets with parchment paper. This makes for easy cleanup and prevents sticking, allowing the ingredients to roast beautifully.
In a large bowl, combine the sliced chicken sausage, bell peppers, onion, and olive oil. Make sure everything is evenly distributed. The olive oil will help the veggies roast and develop flavor.
In a separate, smaller bowl, whisk together the cornstarch, chili powder, kosher salt, smoked paprika, cumin, oregano, garlic powder, and optional cayenne pepper. This spice mix is what gives the fajitas their unique flavor profile.
Sprinkle the spice mix over the sausage and peppers. Stir everything together to ensure that the sausage and veggies are evenly coated with the spices. You want every bite to be packed with flavor!
Distribute half of the mixture onto each lined baking sheet. Spread them out into a thin layer to promote even roasting. Crowding the pan can cause steaming instead of roasting, which isn’t what you want.
Bake for about 15 minutes. Be sure to stir halfway through the cooking time to ensure even browning. You’re looking for a golden brown color on the edges, which indicates that the sausage and veggies are perfectly cooked.
If you want an even browner color, feel free to put the trays under the broiler for a few minutes at the end, but keep a close eye on them! Things can burn quickly under the broiler.
Once done, remove the trays from the oven. Serve the roasted mixture on the flour tortillas, topped with a sprinkle of cilantro and cotija cheese. You can also add any other toppings you love!