Oven temperature is 180C. Place the cleaned guinea hen in a large roasting pan, season with salt and pepper, and roast in the oven. Lemon zest should be finely grated and scraped into a big basin. Mix thoroughly after adding the oil and mustard. Lemon cut in half, placed into the bird.
Peel the potatoes and carrots, then chop them into large slices. Depending on their length, chop the leeks into 3–4 pieces. Mix all the vegetables until evenly covered in the basin containing the oil and mustard.
After peeling, cut the potatoes and carrots into thick slices. Chop the leeks into three to four pieces, depending on their length. In the bowl with the oil and mustard, combine all the veggies until they are uniformly coated.
After the guinea fowl has roasted for 30 minutes, place the vegetables around it, season with salt, and cook for a further 45 minutes.
Put the bacon on top of the chicken and pour the wine over the vegetables and bird. Return the dish to the oven for an additional 15 to 20 minutes, or until the bacon is crisp and the vegetables are soft.