Combine the panko crumbs with the parsley, fresh basil, lemon zest, minced garlic, olive oil, sea salt, and freshly cracked pepper, to taste. Combine with your fingers until evenly mixed.
Squeeze the juice from half a lemon over the halibut fillet. Spoon the Dijon mustard on top of the halibut and spread evenly. Season the fish with sea salt and freshly cracked pepper. Press the panko mixture thickly on top of the mustard–the mustard will help the panko adhere.
Heat the vegetable oil in an OVENPROOF skillet or large cast iron skillet. When the oil is very hot, add the halibut fillet, skin side down, and sear for 3-4 minutes, without turning, to brown the skin.
Transfer the pan to the hot oven for 15-20 minutes or until the thickest part of the halibut flakes easily.
Remove from the oven and cover with a tin foil tent for 5 minutes. Serve the halibut with lemon wedges. Enjoy.