From a book I found in the bookcase when looking for something interesting to do with a sea bream: The Dutch Table: Gastronomy in the Golden Age of the Netherlands.
The fish itself turned out to be rather meh but the sauce was delicious. It goes with any firm non-oily fish; we intend to try zander (pike-perch) next. The recipe says “cook the fish in the oven until just done” so that’s what I did, liberally buttered.
1 tbsp grated fresh ginger
1/2 tsp saffron
salt and pepper
200 ml dry white wine
200 g butter
DO NOT SKIMP ON THE SPICES. You can reduce the butter a bit (I used only 150 g because that was the rest of the package I was using for the fish) without it being any less delicious.
Cut the lemon into pieces, rind and all (so you need an organic lemon and/or scrub it very well). Put everything except the butter into a pan and boil gently for about 15 minutes, or until the lemon looks “done”. Strain (the original recipe doesn’t say this but you really don’t want all those chunks of lemon and threads of saffron and grated ginger on your fish). Let it cool for a bit and beat in the butter.
The original recipe says that will thicken it, but I disbelieve: there’s nothing in this sauce that can thicken it, it’s all fat and liquid. Next time I’ll make some of the butter into beurre manié (equal weight of butter and flour, mixed very well) and thicken the sauce with that, or use an egg yolk. Will report when I’ve tried.
Before you add the butter it seems to be uncomfortably sour, but the butter will fix that, don’t worry.
Period vegetables: cabbage, turnip, carrots, parsnips, fennel, cucumber, or even haricots verts (very new in the 17th century). Bread rather than potatoes.