Quickly rinse the lentils and cook them in the corba broth starting cold, adding only a pinch of salt and a drizzle of oil. Continue cooking for 20 to 25 minutes without ever coming to a boil.
Season the ombrine fillets in a dish with a little salt, pepper, a pinch of crushed poached garlic and a sprig of rosemary; seal with foil and leave to season outside the refrigerator for about 10 minutes.
Cook the fish on the skin side on a well-heated iron pan for 2 minutes, after which close the pan with a lid without ever turning the fillets and let stand 5 minutes more.
On a soup plate arrange a ladleful of more or less brothy lentils according to taste and the fish fillet with the skin side up.
Garnish with buckwheat grain previously toasted in the oven for a couple of minutes, salt a drizzle of oil.

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