Remove the duck meat from the bones. Remove the skin from the meat. Cut the meat into 1/4 to 1/2-inch cubes.
In a large Dutch oven, heat the canola oil over medium-high heat. Add the pork, cook until browned, about 5 to 10 minutes.
Add the chopped garlic and duck meat, cook until duck is browned, about 5 minutes. Sprinkle with ground spice mix, masa harina and flour. Cook, stirring, until flour is lightly browned, about 3 minutes. Add the beer, onions, red pepper, poblanos and jalapeno. Lower the heat to medium, add the chicken stock and chopped canned green chiles.
Crumble the tortillas or corn chips into a blender. Ladle out enough of the chili liquid to cover the tortillas in the blender. Blend until smooth. Add back to chili. Simmer until duck is tender, about 1 hour. Season, to taste, with salt. Keep on simmer until serving.
Remove from heat and stir in the chopped cilantro and lime juice. Serve, garnished with scallions and sour cream.
Heat a dry skillet over medium heat. Add cumin and coriander, cook until spices are fragrant, about 1 to 2 minutes. Transfer to a spice grinder, grind to a powder and transfer to a small bowl. Stir in remaining spices.