Preheat your oven to 375ºF. Rinse and dry the fillets. Season generously with salt and pepper. Pat a little olive oil on each fillet. Combine breadcrumbs with enough mustard to make a fairly dry paste. Coat each fillet with the breadcrumb-mustard mixture and bake until cooked through. Depending on the thickness of the fillets, this will take from 15 to 20 minutes. Serves 6.