Select sauté on the instant pot and adjust to normal.
Add oil to the pot.
When the oil is hot add the mustard seeds.
When the mustard seeds splutter add the fenugreek seeds, red chili peppers, and curry leaves.
After about 30 seconds, add the chopped onions. Stir occasionally.
When the onions turn golden in roughly 2 to 4 minutes add the ginger garlic paste.
Add the chopped tomatoes and sauté for a few minutes until the tomatoes get mushy. Keep stirring.
Add the red chili powder, turmeric, salt, sugar, and ¼ cup water. Keep stirring for about a minute.
Add the shrimp and stir.
Add the remaining ¼ cup water. Make sure nothing is stuck to the bottom of the pot and scrape the bottom of the pot well.
Press cancel.
Secure the lid on the pot with the pressure-valve sealed.
Select manual and cook at high pressure for 1 minute.
Use quick pressure release to depressurize.
Open the lid.
Select sauté.
Add the desiccated coconut and tamarind concentrate. Stir for about 30 seconds.
Add the heavy whipping cream.
Press cancel.
Transfer in a serving bowl immediately.
Garnish with chopped cilantro.