Add a dash of olive oil in your pre-heated pressure cooker and soften the onion, celery and carrot.
When the whole mix is softened, add the chopped tomatoes and mix well.
Sprinkle the salt, pepper and curry (if using).
Now, add the lentils and water and mix well, rubbing the base of the cooker with the spoon to lift any brown bits that may have stuck there and incorporate them into the dish.
Close and lock the lid of the pressure cooker. Electric pressure cookers: Cook for 20 minutes at high pressure. Stovetop pressure cookers: Turn the heat up to high and when the cooker indicates it has reached high pressure, lower to the heat to maintain it and begin counting 10 minutes pressure cooking time.
When time is up, open the pressure cooker with the natural release method - move the cooker off the burner and wait for the pressure to come down on its own (about 10 minutes). For electric pressure cookers, when cooking time is up count 10 minutes of natural open time. Then, release the rest of the pressure slowly using the valve.