Season the cod fillets with a little olive oil, fleur de sel and pepper. Cook in a 180°C oven for approximately 4 minutes. Set aside.
Trim the cauliflowers and set the leaves aside. Season with salt, pepper, garlic and thyme. Sprinkle with toasted buckwheat powder then cook in the butter in a sauté pan. Baste the cauliflower to obtain nice, even colour. Reserve the butter used for cooking the cauliflower for the sabayon.
CAULIFLOWER LEAF BOUILLON
Place the cauliflower leaves in a saucepan and add enough water to cover. Season with salt and simmer over low heat for 20 minutes. Strain and set aside.
In a saucepan over low heat, whisk the egg yolks and the cauliflower leaf bouillon. Slowly drizzle in the reserved butter and mount as for a mayonnaise to obtain a sabayon. Correct the seasoning and set aside at room temperature.
Add the cream to the cauliflower leaf bouillon. Season with salt and pepper. In a bain-marie, blend the mixture with a hand blender to obtain a froth.
Combine the buckwheat flour, cold water and salt in a mixing bowl. Stir the mixture to obtain a homogenous mixture. Add the melted butter and stir again. Let the batter rest 1 hour then prepare thin galettes (crepes) in a non-stick pan. Once cooked, brush with melted butter and sprinkle with fleur de sel. Bake in a 170°C convection oven for 6 to 8 minutes to obtain a crisp buckwheat wafer.
Place the cod in the bottom of a soup plate followed by a generous spoonful of sabayon and a piece of roasted cauliflower. Top with a spoonful of froth followed by a drizzle of meat jus. Finally, gently place the buckwheat wafer on top and finish with a pinch of fleur de sel and a little freshly ground pepper.