Place the potatoes in a stovetop steamer or in the oven and cook until tender, about 45 to 55 minutes. In a blender, puree the jalapeno and broth; set aside. Heat 1 tablespoon of the oil in a large skillet and add the pepper. Cook for 1 minute, stirring constantly. Remove the pepper with a slotted spoon and set aside. Add 1 tablespoon of the oil and saute the onion for 30 seconds, stirring constantly. Remove and add to the pepper. Place the remaining 1 tablespoon oil in the pan and add the chicken. Stir-fry for about 2 minutes. Add the jalapeno puree and cook for 2 minutes more. Add the pepper and onion and cook for 1 minute more, or until the chicken is thoroughly done.
Place the cooked potatoes on a serving plate, slash the tops, and squeeze open. Spoon the fajita mixture on the potatoes, garnish with the scallions and cilantro, and serve the salsa on the side.