In a shallow dish or pan, pour 3 tablespoons ponzu and 2 tablespoons orange juice over the tuna steaks.
Season the steaks to taste with salt and pepper.
Flip to coat both sides of the fish with the sauce.
Set aside and allow the steaks to marinate for at least 20 minutes.
In another shallow dish or bowl, combine the coconut flakes, panko, orange zest, ginger, ½ teaspoon salt and ¼ teaspoon pepper. Mix well to combine.
Press the marinated tuna steaks firmly into the coconut coating to coat all sides.
Place the coated steaks on a plate or baking sheet and refrigerate the coated steaks for 30 minutes.
Meanwhile, mix the sauce ingredients in a small bowl and chill.
In a large skillet, heat the oil over medium heat.
Add the coated tuna steaks and cook on both sides until your preferred doneness (approximately 5 minutes per side, for medium doneness).
Serve hot along with the chilled sauce for dipping.