• Gather all the ingredients.  Preheat the oven to 400ºF (200ºC). For a convection oven, reduce cooking temperature by 25ºF (15ºC).
  
• For teriyaki marinade, combine 1 tsp brown sugar, 3 Tbsp sake, 3 Tbsp mirin, and 3 Tbsp soy sauce in a bowl. Whisk well till the sugar has dissolved completely.
  
• Use a fork to prick the chicken thighs. This will help shorten the marinade process. Put the chicken in a baking dish and pour the teriyaki marinade. Let the chicken marinade for 15 minutes. Turn the chicken once or twice.
  
  
• Bake the chicken in the middle rack at 400ºF (200ºC) for 15 minutes. Turn the chicken once or twice.
  
• Meanwhile prepare the bowls of salsa and sour cream or other condiments. Cut lime if you use any. Cut each avocado into 8-12 wedges. Alternatively, you can slice them, but I like the chunkier texture of avocado in the quesadillas so I cut into 8 wedges.
  
  
• Remove the chicken from the oven and let it sit for a few minutes. Cut the chicken into strips or cubes (I prefer strips, looks better after slicing quesadillas).
  
  
• Heat the griddle pan or frying pan over medium low heat. Place tortillas to warm up and flip once. Place a generous amount of cheese on the tortillas.
  
  
• Then put the fillings and fold in half while the tortillas are pliable.
  
  
• Cut each quesadilla into 3 or 4 triangles. Serve immediately with salsa, sour cream, lime, and cilantro.
  
  

To Store

• You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days and in the freezer for 2 weeks.