| 1. | Stand tomatoes with stem end down. Cut a thin slice off top of each tomato to make a cap and keep aside. Scoop out pulp from each tomato. Keep tomato shells aside. Chop pulp. |
| 2. | Melt butter in a pan. Add onion and celery. Stir fry till onion is transparent. Add mushrooms and tomato pulp. Cook till liquid evaporates, stirring occasionally. Add remaining ingredients except water. Mix well. |
| 3. | Divide mixture into 4 portions. Stuff each tomato shell. Cover each tomato with a tomato cap. |
| 4. | Pour water into cooker. Put grid in cooker. Stand tomatoes on grid. |
| 5. | Close cooker. Bring to full pressure on high heat. Remove cooker immediately from heat. Allow to cool naturally for 5 minutes. Lift vent weight slightly to release pressure. |
| 6. | Open cooker. Serve hot. |