Heat a large Dutch oven with 2 tablespoons of oil over medium-high heat. Add the onions, peppers and garlic, and cook until tender, about 5 minutes. Remove to a plate and reserve.
Add the remaining 2 tablespoons of vegetable oil to the pan. Coat the sirloin with the flour, shaking pieces to remove any excess, and cook until brown on all sides, about 10-15 minutes.
Stir in the tomatoes, tomato sauce, reserved vegetables, chili powder, cumin, salt, black pepper, crushed red pepper flakes, cayenne pepper, beer and Jack Daniels. Cover and simmer, stirring occasionally until meat is tender, about 2 hours.
To thicken the chili, mix the masa and water together in a small cup or bowl. Slowly add the mixture to the chili while stirring.
Simmer uncovered about 30 minutes, stirring occasionally.
Serve hot with corn bread alongside and garnish with chopped onions.