Prepare the monkfish by removing the skin and central bone. Cut into medallions (3-4 per person) and season both sides with salt and pepper.
Peel and finely chop the shallots. Combine with raspberry vinegar in a sauté pan and reduce until about 1 teaspoon remains. Add the fish stock.
Poach the medallions in the broth for 2 minutes per side. Remove to a warm tea towel and reserve. Reduce the cooking liquid to 4 tablespoons, then strain through a fine sieve.
Shape the zucchini into small balls (olives) or slices. Blanch in boiling salted water for 2 minutes. Reserve.
Arrange the medallions on plates or a serving platter. Reheat the sauce, add the zucchini (thin with stock if needed), and season with pepper. Place plates or dish in the oven. Mount the sauce with butter by swirling the pan in a rotary motion until fully emulsified.
Remove from oven, coat the fish with sauce, distribute the zucchini, and garnish with shredded chervil.
Expert tip: Cook zucchini al dente—overcooking diminishes the dish's elegance.
Pro note: Raspberry vinegar is now widely available in supermarkets.
