Heat the oil in a saucepan over medium high heat, Test the heat by adding one cumin seed to the oil; if the seed cracks right away, the oil is ready.
Reduce the heat to medium and add the cumin seeds, carom seeds, asafetida. As seeds crack, add carrots, celery, and ginger. Sauté for about 12 minutes until carrots are very soft.
Puree them in blender with 2 cup of water, on high speed. Add water as needed to puree.
Use the same pan and pour the soup salt and sugar, bring the soup to boil on medium high heat. Add more water if needed. When the soup boils, turn the heat to low and let it simmer for ten minutes.
Serve soup hot, Add the black pepper and lemon juice, in the bowl when ready to serve.