Preheat and Prepare: Preheat your oven to 220°C (200°C fan). Line a large, rimmed baking sheet with parchment paper for easier cleanup. If you don't have a very large baking sheet, it's better to use two smaller ones to avoid overcrowding.

Mix the Seasoning: In a small bowl, combine all the fajita seasoning ingredients: chilli powder, smoked paprika, cumin, garlic powder, oregano, salt, and pepper. Give it a good stir to ensure it's evenly mixed.

Combine Ingredients: In a large mixing bowl, add the sliced chicken, sliced onion, and all the sliced peppers. Drizzle with the 2 tablespoons of olive oil and the juice of half a lime.

Season Generously: Sprinkle the homemade seasoning mix over the chicken and vegetables in the bowl. Use your hands or a large spoon to toss everything together thoroughly until every piece is evenly coated in the oil and spices. What works best for me is using my hands to really massage the spices in.

Arrange on the Pan: Tip the seasoned chicken and vegetable mixture out onto your prepared baking sheet. Spread it into a single, even layer. It's really important not to have everything piled up. For more great chicken ideas, check out our collection of Healthy Chicken Recipes.

Roast to Perfection: Place the sheet pan in the preheated oven and roast for 18-22 minutes. I find that giving everything a quick toss with a spatula halfway through cooking helps it cook more evenly and get charred on all sides. The fajitas are ready when the chicken is cooked through and the vegetables are tender with slightly browned edges.

Warm the Tortillas: While the fajitas are in their last 5 minutes of cooking, warm your tortillas. You can wrap them in foil and place them in the oven for a few minutes, or warm them one by one in a dry frying pan over medium heat for about 30 seconds per side.

Finishing Touches: Remove the sheet pan from the oven. Squeeze the remaining half of the lime juice all over the hot chicken and vegetables. Serve immediately with the warm tortillas and your favourite toppings.