Prepare to cook: Insert stainless-steel inner pot into the Instant Pot. Add 2 tablespoons of the vegetable broth or water to the Instant Pot. Select the Sauté setting and let the Instant Pot heat for about a minute.
Sauté the vegetables: Add the potatoes, corn, onion, and peppers to the Instant Pot. Sauté for approximately 7 to 8 minutes, stirring frequently, until the vegetables have softened. Add the garlic and sauté for 1 additional minute.
Add the liquids and seasoning: Add the coconut milk, broth or water, bay leaf, nutritional yeast, miso, celery seed, paprika, and cayenne pepper (if using) to the Instant Pot. Stir well.
Cook the chowder: Lock the lid into place and set the Pressure Release knob to Sealing. Select Pressure Cook at High pressure for 8 minutes. After the 8-minute timer has finished and beeps, let the pressure release naturally for 10 minutes. Then turn the Pressure Release knob from Sealing to Venting to release any remaining pressure.
Blend the chowder: Open the lid and remove the bay leaf. Add the lemon juice and freshly cracked black pepper, to taste. Then transfer about half the soup to a blender and blend it just until the potatoes have a mashed texture. Return the blended portion to the Instant Pot and stir to combine.
Garnish and serve: Spoon individual servings of corn chowder into bowls. Garnish with toppings of your choice (e.g., fresh basil, cilantro, chives, sliced peppers). Serve immediately.