Pork Loin with Celery

Heat the oil and half the butter in a heavy flameproof casserole just large enough to hold the pork and celery, then brown the pork evenly. Transfer pork to a plate. Add the onion to the casserole and cook until softened but not brown. Place the bouquet garni and dill sprigs on the onion, then place the pork on top and add any juices from the plate. Pour the wine and water over the pork, season to taste, cover and simmer gently for 30 minutes. Turn the pork, arrange the celery around it, cover again and cook for 40 minutes, until pork and celery are tender. Transfer pork the pork and celery to a serving plate, cover and keep warm. Discard the bouquet garni and dill sprigs. Cream the remaining butter and flour, then whisk into the cooking liquid while it is barely simmering. Cook for about 2 - 3 minutes, stirring occasionally. Stir the cream into the casserole, bring to the boil and add a squeeze of lemon juice. Slice the pork, pour some sauce over the slices and garnish with dill. Serve the remaining sauce separately.