Pluck tarragon from the stalks and chop finely. Mix 2/3 of it with the mustard. Clean and wash the leek and cut it into pieces of about 8 cm length. Wrap 1 slice of bacon around each piece. Season the roulades with salt and pepper, brush with mustard and place 1 piece of leek at each end.
Roll up the roulades firmly and pin them with roulade needles. Heat clarified butter in a casserole and fry the roulades in it. Deglaze with wine and pour on 1/2 litre of water. Cover the pan and let it braise for 1 1/2 hours.
If necessary, add a little more water. In the meantime, clean the carrots and peel them so that some green remains. Cook in boiling salted water for 10 minutes. Remove the roulades and keep warm.
Stir the cream into the cooking stock and bring to the boil. Stir in the sauce thickener and bring to the boil again. Season to taste with salt and pepper. Stir in the remaining tarragon. Arrange roulades with the sauce and carrots on plates.
Sprinkle the carrots with lemon peel. Boiled potatoes taste good with it.