Place the limes (cut side down) and chiles on grill and cook until blistered and caramelized, 5 to 7 minutes. Remove from grill and allow to cool.
Juice the limes into a measuring cup to yield about 1/3 cup. Pour the lime juice into a blender and add the cilantro, chiles, honey and salt. Blend, adding oil in a thin stream until the mixture is smooth.