First, finely chop the celery stalks and the onion.
Now melt the butter and sauté the celery and onion in it.
Then add the white wine and let it reduce almost completely.
In the meantime, you can also add the bay leaf and thyme to the sauce base.
Finally, add the fish stock and the cream to the base. Let this simmer and reduce for about ten minutes.
Now strain the vegetables from the sauce to create a smooth sauce. Season with salt and pepper to taste.
Set the white wine sauce aside or keep it warm.
Preparing the potato mousseline
Peel the potatoes, cut them into pieces, and steam or boil them until they are cooked through.
Mash the potatoes with a potato masher. Then push them through a sieve again. We want an extra-fine puree.
First, mix the butter, then the milk and cream into the puree until you have a nice, smooth mousseline.
Keep it warm in the oven.
Preparing the creamed spinach
Crush the garlic cloves with a paring knife and then finely chop them.
Melt the butter in a pan and briefly sauté the baby spinach until it melts. (Tip: use the warm pan you used to sauté the saltimbocca).
Now add the cooking cream and grated Parmesan to the spinach.
Let everything reduce and integrate.
Preparing the monkfish in saltimbocca
Place the sage leaves on the monkfish fillets and then wrap them in the saltimbocca.
Wrap the monkfish in saltimbocca in cling film and refrigerate for 24 hours.
Preheat the oven to 180°C (350°F).
Heat the butter in a pan until bubbling. Then briefly sear the pancetta-wrapped monkfish on all sides.
Then place the monkfish in saltimbocca on a baking sheet lined with parchment paper. Cook for another four minutes in a preheated oven at 180°C (350°F).
Serving the monkfish saltimbocca
Place the silky potato mousseline in a ring in the center of each plate.
Then spread the creamed spinach over the potato mousseline.
Place the monkfish in saltimbocca on the bed of spinach and mousseline.
Spoon the white wine sauce around the potato mousseline on the plate.
Garnish with some finely chopped chives, if desired.