Soften the gelatine sheets in a little cold water. Clean the mushrooms separate the heads from the stems. Cut the larger ones into chunks. Cook the feet in 1 liter of water with the chicken broth. Drain them and cut them into large strips, save the broth.
Squeeze the gelatin sheets to wring them out and melt them in the reserved broth, whisking.
Wash and chop the tarragon and chives. Peel, crush the garlic clove. Brown the duck legs in a skillet over low heat for 5 minutes to soften the flesh. Let cool.
Remove the skin, debone and shred the flesh. In the same skillet, sauté the mushroom heads with the garlic for 3 minutes, stirring, then add the duck meat and fine herbs. Season with salt and pepper, mix and simmer for 10 minutes.
Assemble the terrine:pour a little jelly in the bottom, place a layer of mushroom stems. Cover with a layer of the mushroom head and duck meat mixture, and repeat until all the ingredients are used up.
Pour the jelly up to the brim of the terrine.
Leave the terrine to rest for at least 12 hours in the fridge before serving.
Tip:cut the skin off the skins of the confit duck legs and brown them in a frying pan until crispy. Drain on paper towel and serve as an aperitif.
