Chop onion coarsely. Chop jalapeño finely, removing membranes and seeds if desired. Chop garlic and cilantro.
Preheat large stockpot on medium 2–3 minutes. Add ground beef and sausage; brown 5–7 minutes, stirring to crumble meat, until no pink remains and meat is 160°F. Drain excess fat from pot.
Return pot to heat; add onions, jalapeños, garlic, and chili seasoning. Cook 2–3 minutes, stirring occasionally, until vegetables are tender. Drain pinto beans and corn.
Stir beans, corn, tomatoes (do not drain), and tomato sauce into pot. Bring chili to a boil, then reduce heat to low. Cover and simmer 1 hour.
Stir in cilantro; serve with Cheddar and Jalapeño Cornbread on the side.