Heat the oil in a large saucepan over medium heat. Add the onion and cook until softened, about 3 minutes. Add the garlic, potatoes, and corn and stir to coat. Add the coconut milk, broth, cumin, coriander, salt, and pepper. Bring to a boil. Reduce heat and simmer until the potatoes are tender, about 15 minutes. Add the shrimp and simmer until pink and cooked through, about 3 minutes. Ladle the soup into individual bowls.
Tip: For a creamier chowder, puree half the recipe before adding the shrimp, then return it to the pot and heat until warmed through.