Add canola oil to a pressure cooker and splutter mustard & cumin seeds.
Throw in the curry leaves, ginger garlic paste and turmeric powder.
Cook till the raw smell of the ginger garlic paste goes away.
Add tomato paste and powdered spices including coriander, red chilli and cumin powders.
Cook for around 2-3 minutes. Add the green chillies here as well.
Add Lauki (bottle gourd) and aloo potatoes and coat with masala nicely.
Add water and salt.
Cover the lid of the pressure cooker. Give it three whistles and remove. Let the pressure release by itself.
The Lauki Aloo Ki Subzi at this time will be watery.
Leave it on high flame till you get the desired consistency of masala in the subzi.
Once this is done, add the juice of one lemon, adjust the salt to your desire.
Optionally, you can also garnish it with some garam masala and chopped green coriander.
Serve hot with paranthas right off the gridle.