In large stockpot, cook chicken in 4 cups of water until cooked through and tender. Once tender, shred the chicken and discard the bones. Save the broth. In large saucepan, in oil, fry the onion strips. Add the chocolate to the onion and let it melt. In large stockpot, begin dissolving the mole in 1/4 cup of the chicken broth. Add the onion and the chocolate. Simmer all ingredients together and slowly add the remaining chicken broth until the mole softens. Rinse and drain the Nopalitos. Add the shredded chicken and the Nopalitos to the mole. Bring mixture to a gentle boil. Serve immediately.