Ingredients:

• 2 – 2.5 lb of boneless, skinless chicken breasts
• 1-2 onions
• Olive oil (approx. 1 cup)
• Salt by taste
• 
  Spices:
  1 tbsp of ground black pepper
• 2 tbsp of ground oregano
• 0.5 tbsp of ground coriander seed
• 1 tbsp of ground cumin
• 1 tbsp ground marjoram
• 0.5 tbsp of chili powder

How to make, step-by-step:

1. Prepare ingredients: mix spices in the small bowl, wash chicken on the cold water:
   

   

2. Slice chicken breasts into stripes:
   

   

3. Skin onions and slice them into half-circles:
   

   

4. Put chicken stripes, onions and all spices to the big bowl:
   

   

5. Pour olive oil:
   

   

6. Mix everything, cover the bowl with a lid or plastic wrap and put it to the fridge. Keep chicken marinading in fridge for at least 12 hours:
   

   

7. After 12 hours of marinading, take bowl out of fridge. Warm up a sautéing pan till high temperature, pour chicken with onions to the pan
   

   

8. Fry it all over till the chicken is ready (approx. 15 mins), don’t forget to stir. Salt by taste at the end:
   

   

9. Serve with your choice of the side dish, I prefer Boiled Rice:
   

   

   
   And of course Tzatziki sauce is good addition for any kind of gyros.