Heat the oil in a large skillet over medium heat, and saute the chile, leek, and garlic until tender and lightly browned. Season with salt and pepper.
Mix the chicken broth and tomatoes into the skillet, and season with cumin. Bring to a boil. Reduce heat to low. Place the halibut into the mixture. Sprinkle with lime juice. Cook 15 to 20 minutes until the halibut is easily flaked with a fork. Wrap in warmed corn tortillas to serve.