Beurre Blanc Sauce:
1 pound cold unsalted butter
1 cup dry white wine
½ cup white wine vinegar
1 tablespoon finely chopped shallots
calamansi juice, to taste
1 piece St. Peter’s fish fillet, skin removed
salt, to taste
Prepare beurre blanc sauce. Cut the butter into ½-inch cubes and chill. Heat the wine, vinegar and shallots in a saucepan until the liquid boils, then simmer until the liquid has reduced to about 2 tablespoons. Once mixture has reduced to 2 tablespoons, lower the heat, and add the chilled cubes of butter, one or two at a time, while whisking rapidly. Remove pan from the heat while whisking in the last few cubes of butter. The finished sauce should be thick and smooth. Add calamansi juice for acidity, if desired. Season with salt. Keep warm. Strain the shallots, if desired.
Dry fish with paper towel. Season with salt on both sides. In a sauté pan, sear fish on both sides until golden brown and crispy. Serve with the beurre blanc sauce.