Press SAUTE on Instant Pot. Add olive oil and once it's hot, add minced garlic, onions, green chili, and saute till onions soften.
Add diced bottle-gourd, water or vegetable stock, and salt.
Furthermore, close the lid on the pot and set the pot to MANUAL/PRESSURE COOK (High Pressure) and timer to 5 minutes.
When the instant pot beeps, let the pressure release naturally. Open the lid.
Puree soup using a hand blender until smooth. If you don't have a hand blender, puree in a blender in batches once slightly cooled.
Then add crushed black pepper for seasoning and salt if needed. Also, if you think the soup is too thick, add water or vegetable broth to the soup and simmer it for 2 minutes until hot.
Add 1 tablespoon of lemon juice and garnish with coriander leaves. Mix well. Instant Pot Lauki ka Soup is ready to serve.