Season chicken breasts with salt, pepper, oregano and thyme and place on a frying pan at high heat to sear. The chicken does not need to be entirely cooked at this point, we just want to get a nice golden exterior.
In a pot on medium heat add the boiling water, the onion, celery, thyme, oregano, garlic, chicken breasts and chicken carcass (if you have saved it). It will cook here for approximately 2 hours to give the stock flavor. The broth should have a lot of flavor. You can add in some chicken stock cubes to add flavor if you are not satisfied with the broth.
Once the chicken breasts are completely cooked, take them out of the stock pot, shred them and set them aside for later. Strain the stock into a large bowl since we will be using it to cook the rice.