Sole Mornay takes shallow-poached sole fillets and covers them in Sauce Mornay — a béchamel enriched with Gruyère and Parmesan, egg yolks, and cream — then gratinées the dish under the salamander until the surface is bubbling and golden. It occupies the richer end of the sole spectrum, where the cheese sauce provides a savoury counterpoint to the sweet, delicate flesh. The fillets are shallow-poached in the standard manner (fumet, white wine, shallots, buttered cartouche, 8-10 minutes at gentle simmer). The cuisson is strained and reduced by half. Sauce Mornay is prepared separately: a medium béchamel (30g butter, 30g flour, 500ml milk) is enriched with 60g finely grated Gruyère and 30g Parmesan, stirred until melted and smooth. Off the heat, beat in 2 egg yolks mixed with 50ml cream. Combine 200ml of the Mornay with the reduced cuisson — this lightens the cheese sauce and adds fish flavour. Butter a gratin dish, spread a thin layer of sauce on the bottom, arrange the poached fillets, and nap generously with the remaining sauce. Scatter a fine layer of grated Gruyère and dot with butter. Gratinée under the salamander at 280°C for 2-3 minutes until bubbling and spotted with gold. The cheese must melt and colour but not burn — the bitter compounds in scorched cheese would destroy the delicate balance. The dish sits at the intersection of the poissonnier and saucier stations, requiring mastery of both poaching and béchamel-family sauces.
Sauce Mornay: béchamel + Gruyère + Parmesan + egg yolks — the cheese ratio matters (2:1 Gruyère to Parmesan) Mix reduced cuisson into the Mornay — this prevents the cheese sauce from overwhelming the fish flavour Egg yolks added off heat to prevent curdling Gratinée under fierce heat briefly — golden spots and bubbles, not a solid brown crust Butter the gratin dish and add a sauce layer beneath the fish to prevent sticking
Comté can substitute for Gruyère with slightly nuttier results — both are excellent gratin cheeses A dusting of dried breadcrumbs over the final cheese layer before gratinéeing adds a delicate crunch that contrasts the creamy sauce For a lighter modern version, replace half the béchamel with the fish cuisson thickened with a touch of potato starch
Using only one cheese — the combination of Gruyère (melt and stretch) and Parmesan (umami depth) is essential Scorching under the salamander — burnt cheese is acrid and overpowers the sole Making the Mornay too thick — it should flow over the fish, not sit in a solid mass Forgetting the cuisson addition — without it, the dish tastes of cheese, not of fish with cheese Adding egg yolks over heat — the sauce scrambles and becomes grainy
Escoffier, Le Guide Culinaire; Larousse Gastronomique