Place the potatoes, corn, jalapeño, ground cumin, oregano, and coriander into the crock of a 5 or 6-quart slow cooker.
Cover and cook on low for 6-8 hours or high for 3-4 hours.
About 30 minutes before serving, scoop out about half of the potatoes and place in a large bowl. Add coconut milk, and mash until potatoes are almost smooth. Return to slow cooker crock and stir to combine. Cover and continue cooking until all ingredients are heated through.
Season with salt and black pepper, to taste, and stir to combine. Sprinkle with chopped cilantro for serving if desired.