Heat a large pot over medium heat. Pour in the olive oil. Add the onions, celery, and red bell pepper. Sauté until onions are translucent and vegetables are soft, about 10 full minutes. Season with salt and pepper.
Add the sun dried tomatoes, thyme, smoked paprika, chili flakes, and garlic to the pot. Stir until very fragrant, about 1 minute.
Add the potatoes and corn to the pot and stir. Season generously with salt and pepper. Pour in 6 cups of vegetable stock and stir. Bring the pot up to a boil and then reduce the heat to a simmer. Simmer, covered, until the potatoes are tender, about 25 minutes.
Remove about a ⅓ of the soup and place it in a blender. Add the non-dairy milk and miso too. Blend this mixture on high until completely smooth. Pour the puréed portion of the chowder back into the pot and stir, bringing it back up to a simmer.
If the chowder is too thick for your liking, add some more vegetable stock to loosen it up. Stir in the lemon juice.
Check the chowder for seasoning and adjust to suit your taste (more salt, pepper, chili, lemon etc). Serve the corn chowder hot with chopped chives/parsley on top and extra black pepper.