Wash lentils and soak in 2 cups of water for 1 hour or longer. Once soaked, the lentils should be about double in volume.
Heat 4 cups of water in a pressure cooker on medium high heat. Next add soaked lentils, salt, turmeric, black pepper, ginger, carrots, green beans, celery, and tomatoes.
Close the pressure cooker and put the weight on (or seal the exhaust).
As the pressure cooker starts steaming turn the heat down to medium and cook for about 6 minutes.
Turn off the heat and wait until the steam has stopped before opening the pressure cooker.
Mix dal well, if dal is thick add more boiling water and make the consistency as you desire. Soup should be chunky.