Heat a large skillet over medium heat. Add the pepitas and toast, stirring occasionally, until they begin to pop, 5 to 7 minutes. Transfer 2 tablespoons pepitas to a small bowl and add the rest to a blender. Add the cumin seeds to the same skillet and toast until dark brown, about 1 minute. Add to the blender; reserve the skillet. Add the salsa verde, 1/2 cup cilantro, the allspice and 1/2 cup water to the blender. Blend until smooth, adding up to 2 tablespoons more water if needed.
Pour the puree into the reserved skillet; stir in the chicken and bring to a simmer over medium-high heat. Cook, stirring occasionally, until warmed through, about 5 minutes; thin with up to 1/4 cup water if needed. Season with salt and pepper.
Toss the bell pepper, radishes, lime juice and remaining 1/2 cup cilantro in a small bowl; season with salt and pepper. Warm the tortillas in a large dry skillet.
Divide the tortillas, bell pepper salad and chicken among plates. Sprinkle with the reserved pepitas; serve with lime wedges.