In a skillet or saucepan, heat oil over medium heat. Once hot, add the chicken fajitas. They will release juice; remove it and set it aside in a cup for later use. Let the fajitas brown slightly.

Once they are partially browned, remove them from the heat and place them on a plate. In the same skillet, sauté the onion until it becomes translucent.

Remove the onion and add the bell peppers, tomatoes, and mushrooms to the skillet. Let them release their juices.

Add the fajitas, onion, and reserved juice back into the skillet. Then add the beer, pepper to taste, and spices. Stir everything together and let it rest for 10 minutes. Enjoy!