In a large pot over medium heat, sauté the onion in the oil until softened. About 3 minutes. Then stir in the flour and chili powder and continue to cook for another 2 minutes. Stirring to prevent burning.
Add in the water, tomato paste, cumin, garlic, cayenne, salt and pepper. Stir to combine until paste has broken up and dissolved. Let simmer and thicken for about 3-5 minutes.
Add in chicken broth, shredded meat, diced chiles, squeeze of half a lime, 1/2 of the cilantro and hominy. Stir to combine and let simmer for 10 minutes or so to combine all the flavors. Serve immediately and top with lime wedges, sour cream, fresh cilantro and avocado if you want.