Chicken fajitas recipe, with bell peppers and onions

Ingredients

• 4-6 flour or corn tortillas
• 2 chicken thighs (skinned and boned)
• 2 chicken breasts (skinned)
• 1 small brown onion
• 1 small red onion
• 1 red bell pepper
• 1 green bell pepper
• 1 tbsp smoked paprika
• 2 tsp ground cumin
• 1 tsp chilli flakes (I like ancho, arbol, or pasilla)
• ½ tsp ground cinnamon
• 1 tsp oregano (use Mexican oregano, ideally)
• 2 tsp sugar
• Salt
• Neutral cooking oil (such as vegetable or rapeseed oil)
• Optional toppings such as sliced avocado, guacamole, sour cream, salsa, cheese, or refried beans