In a small saucepan, put all the ingredients of the court-bouillon and bring to a boil, then reduce the heat and let simmer for 10 minutes covered. Turn off the heat and add the salmon fillet. Cover and let rest for 5 minutes. Turn the fillet and let rest for 5 minutes more. Remove the salmon from the saucepan and let it cool. In the food processor, put half of the smoked salmon in pieces, the butter, mayonnaise, lemon juice and zest, dill and chives. Pulse until a homogeneous texture is obtained. Transfer the preparation to a large bowl, then add the rest of the smoked salmon in pieces and the poached salmon, crumbled with a fork. Mix gently to combine all the ingredients, while keeping the salmon in pieces. Pack the preparation into small pots. Refrigerate until the tartinade is firm. If you plan to store the tartinade for more than 3 days, it’s better to seal the surface with clarified butter, melted and cooled.