Wash rabbit pieces and pat dry with paper towels. Arrange them in a single layer in a flame-proof casserole dish, and season with salt and pepper. Pour the oil over, and sprinkle with celery, garlic and onion. Cover the casserole tightly and bake in a preheated moderately slow oven, 170C (325F) for 2 hours, turning the meat once or twice. During this time, the rabbit will produce quite a lot of juice. Place the casserole on top of the stove over high heat, remove the cover, and cook until the liquid in the dish has almost evaporated. Add wine, rosemary, tomato paste and sugar to the pan, and stir to combine. Reduce heat to low and cook rabbit for another 15 minutes, basting with sauce in the pan and turning the pieces over two or three times. Eason to taste with salt and pepper and serve from the casserole with crusty bread and a green vegetable.
