Bring the stock to a boil in a saucepan and poach the chicken; shred chicken and reserve stock. In a large saucepan, heat the oil over moderate heat. Saute the onions and celery, stirring, about 5 minutes or until soft but not browned. Add rice to saucepan and stir well to coat thoroughly with the oil mixture. Cook, stirring, 2 to 3 minutes longer or until rice becomes almost translucent. With a ladle, pour about 125 ml of the chicken stock into the rice mixture and stir well to combine. Bring the stock to a boil, then gently simmer, uncovered and stirring occasionally, until most of the liquid is absorbed.

Repeat the process, adding about 125ml stock at a time, until rice is almost tender but still firm to the bite, using as much stock as necessary. Add asparagus with last 125ml of stock. Stir in chicken, cheese, lemon juice, salt and pepper. Remove from heat, cover, and allow to stand about 5 minutes.