Dice the onion, celery, sweet potato, and red pepper. Mince the garlic and ginger or smash them in a mortar and pestle.
Heat a large pot over medium heat.
Add the oil, then add the onions, celery, and salt - saute for 5 minutes
Add the red pepper, ginger, garlic, and spices and saute for another minute.
Add the yams, the corn, and the coconut milk - with enough water to barely cover the vegetables. Bring to a boil, then cover and simmer for 10-15 minutes, or until the yams are tender.
OPTIONAL: Take a potato masher and mash up some of the soup right in the pot. It'll break up some of the sweet potatoes and help thicken the chowder.
Finish with a few pinches of thinly sliced leafy greens - this could be thinly sliced Swiss chard, spinach, kale, or even fresh herbs like cilantro.
Serve with a squeeze of lime or lemon and a few cracks of black pepper to brighten up each bowl.