Brown the bacon: Brown the bacon in a large pot over medium heat until golden and crispy. Remove and set aside.
Brown the duck legs: In the same pot, brown the duck legs on all sides, then set aside with the bacon.
Sauté vegetables: Add celery, carrots, leek, garlic, and onions to the pot, and sauté for 3–5 minutes until they start to soften.
Add tomato puree: Stir in the tomato puree and cook for a minute to release the flavors.
Combine and cook: Return the bacon and duck legs to the pot, add lentils, white wine, water, soy sauce, and the herb bouquet. Stir well and bring to a boil.
Braise in oven: Transfer the pot with a lid to a preheated oven at 185°C and braise for about 1.5 hours, or until the duck legs are tender and flavors have developed.