Pour the vegetable broth into the Instant Pot. Add the scallions, garlic, ginger, sweet potatoes, tomatoes, red curry paste, red lentils, salt, and tamari or soy sauce, and lite coconut milk. Stir to combine.
Secure the lid and set the Pressure Release to Sealing. Select the Pressure Cook setting at high pressure and set the cook time to 10 minutes.
Once the 10-minute timer has completed and beeps, allow a natural pressure release for 10 minutes and then switch the Pressure Release knob from Sealing to Venting to release any remaining steam.
Add the lime juice, agave or sugar, and chopped cilantro. Stir to combine. Taste the soup and adjust the seasonings as needed, adding more salt for saltiness, lime juice for acidity, or agave/sugar for sweetness. If the soup is too thick for your liking, add some vegetable broth or water, and stir to heat through until the soup has thinned out a bit.
Ladle soup into bowls and garnish as desired. Store leftovers in the fridge for up to 4-5 days. The soup thickens as it rests, so if you’re serving leftovers, heat it up on the stove with a bit of water or vegetable broth.