In a small bowl, whisk together the orange marmalade, Dijon mustard, lemon juice, apple juice, chopped basil, and red pepper flakes until smooth.
Preheat your outdoor grill to medium-high heat and clean the grates thoroughly.
Season the halibut fillet lightly with salt and black pepper on both sides.
Place the halibut on the grill, skin-side down, to prevent sticking and allow for easier handling.
Brush the top of the fillet generously with half of the prepared orange Dijon glaze.
Grill for about 10-12 minutes or until the fish becomes opaque and flakes easily with a fork.
Brush the remainder of the glaze over the fish during the last 2 minutes of cooking.
Carefully remove from the grill and serve immediately.