Instructions

1. 1
   Place chiles and 3 cups water into a medium stockpot, and bring to a boil. Remove from heat and steep for 30 minutes to soften. Strain into a bowl, reserving the cooking liquid.
2. 2
   Place the chiles and some of the liquid into a blender, and purée until smooth. Add more liquid as necessary to form a smooth sauce. Pass sauce through a fine mesh strainer to remove any seeds and the tough skins; set aside.
3. 3
   Cut the beef into 1–2-inch chunks. In a medium bowl, combine flour, salt, and pepper. Dredge the beef chunks in the seasoned flour; set aside.
4. 4
   Heat olive oil in a large pot over medium heat. Sauté onion until tender and translucent, about 5 minutes. Add beef chunks a few at a time, so as not to overcrowd the pot, and cook until evenly brown. Remove cooked meat, and continue browning remaining meat.
5. 5
   Return reserved cooked meat to the pot. Stir in pureed chile mixture. Add beef stock to just cover beef chunks, or to personal preference. Bring to a boil over medium heat.
6. 6
   Reduce heat to lowest setting, and simmer for 3 hours, or until meat is tender. If necessary, adjust with more stock during cooking.