Heat oil in a large stock pot over medium-high heat. Once oil is shimmering, add onion and garlic and season with salt and pepper. Cook until onion is translucent, about 5 minutes. Add chard stems, bell pepper, and jalapeño, and season again with salt and pepper. Let cook, stirring occasionally, until pepper is tender, about 4 minutes more.

Add cumin and stir to combine. Add wine and scrape any browned bits stuck to the bottom of the pot. Add corn, potatoes, and stock and bring to a boil. Reduce heat to low and simmer until potatoes and cooked through, about 30 minutes. Partially blend to desired consistency. Taste and adjust seasoning as needed. Serve each bowl with a dollop of sour cream, some diced avocado and a few slices of red chile.