Rub the meat well with 1 teaspoon salt, pepper, and olive oil.
Combine the ground coffee, cocoa powder and cinnamon and mix well. Spread the mixture over a work surface and roll the beef in it until coated evenly. Allow to marinate approximately 30 minutes at room temperature ¿ it won't cook evenly if it's cold.
Heat a saucepan over medium-high heat. Add the butter and saute the onion and garlic cloves until nicely browned. Add chiles and tortilla pieces and lower the heat, gently sauteing until they are golden brown. Add the chicken stock. Bring the stock to a boil, then simmer, lightly covered, for 10 minutes. Remove the stock from the heat and allow to cool.
Preheat the oven to 400 degrees F.
Transfer the ingredients to a blender and puree for 1 minute or until smooth. Pass the sauce through a sieve to remove any coarse pieces. Add the cream, remaining 1 teaspoon salt and brown sugar and blend. The sauce should not be too thick. If too thick, add some more chicken stock or water; it should be a very light consistency. Reserve.
Place the beef on a roasting rack in a roasting pan. Roast in the oven for 10 minutes. Immediately lower the heat to 250 degrees F and roast for 20 minutes. Check the beef's internal temperature with a meat thermometer (125 degrees F for medium-rare, 135 degrees F for medium). If further cooking is necessary, return the beef to the oven (still set at 250 degrees F) and slowly roast to the desired temperature. Remove the beef from the oven and let rest for a few minutes. Before carving, remove the string.
To serve, slice the filet into 1/4-inch thick slices. Ladle the pasilla chile broth over the filet.
Recipe courtesy of Chef Robert del Grande, Cafe Annie, Houston, TX