Liberally salt and pepper the fish fillets. Add oil to a pan heated to medium heat and lay the fish fillets onto the oiled surface. Cover the pan and cook for 6-10 minutes (depending on thickness of fillets), or until fully cooked inside (~140ºF/60ºC), flipping the fish halfway through cooking. Transfer the fish to a plate and set aside. Add the butter and garlic to the pan and heat, swirling the pan occasionally, until the butter has start to turn a golden brown. Add the wine and broth, stirring well. Allow the sauce to reduce by half, then add the whipping cream. Allow the sauce to cook for a 2-3 minutes, then add the tarragon, stirring in completely. Add the fish back to the pan, spooning the sauce over the fish. Transfer to a serving dish. Serve immediately.