A good early modern sauce for fish from Mary Cannon’s Commonplace Book , edited with commentary by Marjorie Quarton.

Mrs. Cannon’s commonplace book was compiled in Dun Laoghaire outside Dublin at the outset of the eighteenth century. It relies on a traditionally British sauce base of anchovy and oysters, and in the robust British manner is highly seasoned, in this case with horseradish and shallot. Extremely good with any grilled, roast or baked fish and worth widespread revival.

• 1 cup fish stock or oyster liquor
• 1 Tablespoon malt vinegar
• 2 minced anchovies or a heaped teaspoon anchovy paste or essence ( see the notes)
• 3 or 4 chopped oysters
• about a Tablespoon finely grated fresh horseradish
• a minced shallot
• 2 Tablespoons cold unsalted butter cut into small cubes

1. Combine the stock, vinegar and anchovy in a small saucepan, bring it to a boil and simmer for 15 minutes.
2. Add the horseradish and cook the sauce until it steams again, then add the oysters to heat them through.
3. Stir in the butter to thicken the sauce and serve it hot with the fish.

Notes:

-Mrs. Cannon intended her sauce for ‘boyled,’ actually simmered, fish, so had to hand ‘ye Liquor of your ffishe,’, but the sauce is best made with oyster liquor if you have some. If you have neither liquor or stock use bottled clam juice instead.

-In similar vein, if you have no fresh horseradish, use a like amount of bottled but cut the amount of vinegar in half to compensate for the vinegared bottled condiment.

-Mrs. Cannon does not specify any species of vinegar and what have used whatever she had. You can too; a Riesling or Champagne vinegar would produce a brighter sauce.