Pre-heat the Instant Pot using the SAUTE function. When the display reads HOT, add olive oil and arrowroot powder, whisk to combine. Add the onion and celery. Cook, stirring often, until the veggies have softened and the onions begin to appear translucent.
Add the vegetable broth, coconut milk, corn kernels, sweet potatoes, sea salt, dried onion, red pepper flakes, black pepper, and chopped cilantro stems.
Place the lid on your pressure cooker. Make sure the vent valve is in the SEALING position. Press the cancel button. Using the display panel, select the MANUAL/PRESSURE COOK function, high pressure. Use the +/- buttons until the display says 8 minutes.
When the cooker beeps to let you know it’s finished switch the pressure knob from the SEALING to the VENTING position. Use caution while the steam escapes—it’s hot.
Ladle out two cups of the soup and set them aside. Using an immersion blender, blend the soup until it reaches a chowder constancy and stir back in the two cups of soup. Let cool and serve with a sprinkle of fresh cilantro leaves, sea salt, and black pepper to taste.