Heat a large, heavy bottomed pot over medium heat. Pour the olive oil into the pan and let it warm for about 30 seconds, until it begins to shimmer. Add the diced onions to the pot and saute the onions in the oil. Cook until the onions are soft and translucent, stirring occasionally. About 7-8 minutes. 

Add the minced garlic and chili powder, oregano, paprika, and cayenne pepper to the pot. Stir to coat the onions in the spices and cook for about 1 minute until the spices are very fragrant. Stir often to ensure the spices do not burn.

Season the chicken thighs with salt and pepper and nestle the chicken among the sauteed onions in the pot. Pour the water into the pot. 

Place a lid over the pot and let the sauce simmer and chicken cook, at least 25-30 minutes. The chicken can cook for up to 1 hour.

Turn the heat off from the stove and remove chicken thighs from the pot. Let cool slightly and then shred.

Add the shredded chicken back into the pot and stir to coat the chicken in the sauce. Bring sauce to a simmer over medium heat. Simmer for 5 minutes to slightly reduce the sauce.

While the sauce simmers, sprinkle about 1 tablespoon of shredded cheese onto each tortilla. Microwave the tortillas for 20 seconds, to melt the cheese and soften the tortilla.

To build the taco, layer a scoop of shredded chicken over the melted cheese, followed by a scoop of pickle de gallo, and a dollop of dill pickle ranch dressing. Enjoy!