Toss the beef with 1 tablespoon each brown sugar and salt in a large bowl. Heat the vegetable oil in a large skillet over medium-high heat. Cook the beef in batches until browned on all sides, 4 to 5 minutes (do not crowd the pan). Transfer to a 5-to-6-quart slow cooker.
Reduce the heat to medium, add the onion to the skillet and cook until soft, about 5 minutes. Stir in the garlic, chiles, cumin and chili powder and cook 3 minutes. Add 1 1/2 cups water and the tomatoes and simmer, scraping up the browned bits from the bottom, about 3 minutes. Transfer to the slow cooker, cover and cook on low, 7 hours.
Add the remaining 1 tablespoon brown sugar and the hot sauce to the chili. Serve with scallions, cilantro and/or sour cream for topping, and chips, if desired. (Reserve 3 to 4 cups for Chili-Corn Casserole.).
Use the leftover chili to make Chili-Corn Casserole.