Heat Instant pot on Saute mode. Add oil, followed by onions, garlic and ginger; cook till the onions are translucent, about 3~4 minutes.
Add the chopped potato, carrot and cook for 3~4 minutes. Next add the tomatoes, curry powder, turmeric and cook till tomatoes are mushy.
Stir in the lentils and broth; season with salt and pepper. Close the lid and put on 'Sealing'. Turn off 'Saute' mode and turn on 'Manual/ Pressure cook' mode. Cook on high pressure for 6 minutes.
Once done, let the pressure release naturally.
Use a immersion blender to blend the soup into a smooth mixture. You can leave some chunky to have some texture to the soup.
Stir in coconut milk and turn on Saute mode and cook till heated through, about 3~4 minutes. Mix in lime/ lemon juice and garnish with cilantro. Serve warm with roasted cashews on top. Enjoy!!