Preheat the oven to 425°. In a small bowl, mix together the panko, parsley, lemon zest and ½ teaspoons salt and ½ teaspoon pepper. Add the 2 tablespoons olive oil and mix well until the crumbs are evenly coated.
Place the salmon fillets on a board and brush the Dijon mustard evenly on the top. Sprinkle with salt and pepper. Press the panko mixture thickly on top of the mustard on each salmon fillet. The mustard will keep the panko from sliding off.
Heat the 2 remaining tablespoons of olive oil over medium high heat in a large 12 inch cast iron skillet or large ovenproof skillet. When the oil is very hot add the salmon fillets, panko mixture up, and sear for 3 to 4 minutes. Do not turn and transfer the pan to the hot oven for 5 to 7 minutes until the salmon is almost cooked and the panko is browned.
Remove from the oven and cover allowing resting for 5 or so minutes. Serve with the lemon wedges.