In a thick, even-bottomed saucepan, reduce the shallot, bay leaf, peppercorns, lemon wedge, and white wine, until almost dry. Add heavy cream, reduce by half, whisk in cold butter on very low heat until butter is just melted. Turn off heat, strain, season, add herbs and lemon zest.
Season and sauté all ingredients with olive oil until potatoes are golden brown and mushrooms and onions are soft, about 5 to 8 minutes.
Divide between two deep dinner plates, place fish on top of hash base, and drizzle herb butter sauce on top. Garnish with a lemon wedge and any leftover fresh herbs.
This recipe is courtesy of Van Rensselaer’s at 1019 State Highway (Route 6) in South Wellfleet and it also appeared in the 2013 Early Summer issue of Cape Cod HOME.