Roast the poblano directly over a gas flame or under the broiler, turning, until charred. Let cool. Peel, seed and chop the poblano.
Preheat a cast-iron skillet. Add the tomatoes, tomatillos and garlic and cook over moderate heat, turning, until charred. Peel the garlic; transfer to a food processor. Add the tomatoes, tomatillos, poblano, red chile and scallion and pulse until chunky. Add the lime juice and season the salsa with salt.
Microwave the duck at high power for 1 1/2 minutes, until the skin is warm. Remove the skin from the legs in 1 piece. Line a plate with paper towels and lay the skins on top. Microwave at high power for about 5 minutes, until the skin is browned and sizzling. Remove the skin from the paper towels and let cool completely. Cut the crisp skin into thin strips.
Shred the duck meat. In a skillet, simmer the broth, soy sauce and five-spice powder. Add the duck and toss until heated through.
Serve the tortillas with the salsa, duck, cracklings and cilantro.