Mix the verjuice and white wine.
Finely grind the ginger, cloves, cinnamon, grains of paradise, and saffron. Mix the ground spices with 1/4 cup of the verjuice and white wine mixture, and leave them to steep in the refrigerator for at least an hour, preferably overnight.
Finely grind the almonds. Mix the almonds with the remainder of the verjuice and white wine mixture, and leave them to steep in the refrigerator for at least an hour, preferably overnight.
Remove any scales or bones from the perch fillets. Fry the perch in a frying pan with most of the olive oil over a low-medium heat about four minutes per side, drain, and refrigerate.
Fry the pine nuts in a frying pan with the remainder of the olive oil over a very low heat until golden brown, drain, and set aside. Be very careful, as they can go from golden to burnt in seconds.
Parboil the parsley for a few seconds in a saucepan of boiling water, drain, and set aside.
To make the sauce, take the almond liquid, sieve (to remove large lumps or almond skin), and put into a saucepan. Bring to a boil over gentle heat, stirring occasionally, then remove from the heat.
Take the spice liquid, sieve (to remove any large lumps), and add it to the sauce. Add the sugar. Simmer over gentle heat for fifteen minutes. Remove from the heat. If it begins to solidify and form a very soft custard as it cools, it has been heated enough. If it isn't doing so, simmer for another five minutes. Check the taste, and add more sugar if it is far too sour for you (but it should be sour).
Pour a thin layer of sauce into the serving dish, arrange the fried fish fillets on top, and pour the remaining sauce on top of the fish.
Arrange the pine nuts and parsley leaves as a garnish to the dish. It may be served at once, or covered and refrigerated overnight.
Note 1: If you can't obtain verjuice, lemon juice is a suitable alternative.
Note 2: North American cinnamon is actually cassia. Use real cinnamon if available. Cinnamon is not mentioned in the particular original recipe, but is mentioned in other related recipes from similar dates, so I added it.
Note 3: Fishes mentioned in Le Viandier de Taillevent as suitable for frying include pickerel, loach and tench (both related to the carp), perch, and sole.
Note 4: I use unrefined turbinado cane sugar.
The original recipe (in translation) is here