Season duck legs with salt, pepper, garlic, and thyme in a tray.
Cover and marinate in the fridge for 2 to 3 hours.
Preheat the oven to 140°C.
Rinse the duck legs under cold water and pat dry.
Place duck in a casserole dish and submerge in melted goose fat.
Bake in the oven or simmer on the stove for 3 to 4 hours.
Skim off the fat and set the duck aside.
Boil lentils in a saucepan and remove any surface foam.
Add aromatics and simmer for 10 minutes until al dente.
Strain lentils and reserve 30ml of the cooking liquid.
Mix lentils with vinaigrette, reserved liquid, and chervil.
Brush duck with honey and sear in a pan for 5 minutes until crisp.
Serve the duck legs on top of the lentils.