After washing and patting dry the fish fillets, coat them with a light layer of the mustard, then with a mixture of the fresh herbs and a sprinkling of salt and pepper.
Use two skillets. Heat the olive oil in each skillet and sear the exterior of the fish, two fillets at a time, about a minute per side.
Pour 1/2 cup of fish stock or water into each pan around the fish, and put the skillets into the preheated 400-degree oven for 8-10 minutes.