Heat oil in a heavy-bottomed saucepan, and saute scallions, celery, carrot, and garlic over medium-low heat for about 20 minutes, stirring frequently, until the vegetables have caramelized lightly. Add the red wine and beef stock and bring to a simmer.
In a stainless steel mixing bowl, whisk together the toasted flour and butter, add the tomato paste, then gradually ladle in the hot stock, whisking as you go to make a smooth sauce. Add the sachet d'epices of parsley, thyme, bay leaf, and peppercorn, reduce heat to low, and simmer for about 50 minutes. Skim any impurities off the surface.
Heat oil to 350 degrees F in a deep-fryer.
Mix the chili powder, salt and garlic powder in a shallow bowl and stir in flour. Skewer chunks of chicken using bamboo skewers which have been pre-soaked in water, and dip chicken into warm water, then coat with seasoned flour. Fry until cooked through (about 6 minutes) and serve with Espagnole sauce. (Alternatively, these can be grilled by eliminating the flour and dipping the moistened skewered chicken into the mixed seasonings, then grilling until cooked through.)