Galangal-Tarragon Sauce for Seafood

You can substitute fresh ginger for the galangal in this recipe, but the latter gives the sauce an added depth, and it finishes with a delicate accent of spice rather than the bite of heat that ginger delivers. The sauce is made in the same way as mayonnaise is made, but the proportion of liquid turns it into a thin emulsion, perfect for pooling on a plate with a cooked fish fillet set on top. Serve it with grilled, broiled, or pan-seared salmon or halibut. It’s also terrific with shrimp. F