In a large heavy-bottomed pot, heat 1½ tablespoons vegetable oil over medium heat; add half the meat and brown on all sides, 3 minutes per side. Repeat with the remaining oil and meat.
Return the meat to the pot, and add garlic, onion, and jalapeño; stir to combine. Add remaining chili ingredients, making sure the beef stock covers everything. Bring to a simmer, then reduce heat to low and let simmer uncovered, 1½–2½ hours, stirring occasionally.
Chili is done when you can easily break apart the meat with a wooden spoon. Do this with half of the meat, leaving some in cubes.
Assembly: Ladle chili into individual serving bowls and top with cheddar, scallions, sour cream, and cilantro. Serve immediately.
Chili keeps in fridge for 2 weeks, or you can store in freezer in freezer bags.