Add tomatoes, carrots, beet, cinnamon stick, and salt to the Instant Pot. Add 3 cups of water. Close the Instant Pot with the pressure release valve set to sealing. Pressure Cook for 10 minutes. Allow natural pressure release.
Open the Instant Pot, remove the cinnamon stick, and discard it. Blend the soup using an immersion blender until smooth.
Set the Instant Pot to Saute mode. Mix arrowroot flour in ΒΌ cup of water and slowly stir it into the soup.
Heat ghee in a small pan over medium-low heat. Add cumin seeds and turn off the heat once they start to sizzle. Add the tadka to the soup.
Add black pepper and adjust salt to taste. Bring the soup to a gentle boil and enjoy hot with crunchy croutons.
