How to Make It
Roast the poblanos directly over a gas flame or under a preheated broiler, turning, until charred all over. Transfer the chiles to a bowl, cover with plastic wrap and let steam for 15 minutes. Peel, seed and stem the chiles, then cut them into 1/4-inch strips.
Light a grill or preheat a grill pan. Brush the chicken all over with oil and season with salt and pepper. Grill over moderately high heat, turning once, until the skin is crisp and browned, about 8 minutes. Transfer the chicken to a carving board and cut into 1/2-inch strips.
In a medium bowl, toss the poblano strips with the chicken and cilantro and season with salt and pepper. Serve the chicken-poblano filling in the warm tortillas with the crema, lettuce, onion and lime wedges.