Heat oil and butter in large stockpot. Add garlic, cook until aromatic- about a minute. Add pork to pot and sautee until it starts to brown, about 5 minutes. Add onion, tomato, corn, and green chile. Stir and cook until onions are translucent. Add potatoes, stock, and enough water to just cover the potatoes. Salt and pepper to taste. Bring mixture to a boil, reduce heat to medium low, cover and simmer until potatoes are soft, about 20 minutes. Serve with cornbread.