Pat dry the cubed beef to remove excess moisture.
Place a large cast iron pan or Dutch oven on medium-high heat. When hot, add the canola oil and cubed beef without crowding the pan (see note).
Sauté the beef for 5 minutes, turning every few minutes until brown on all sides. Repeat with remaining beef if batches are necessary.
Reduce heat to medium and add the onion, garlic and green pepper to the beef. Sauté for 3-4 minutes.
Add the tomatoes, cumin, optional oregano, optional jalapeño, salt, pepper and broth. Bring to a boil.
Reduce heat to low and cover the pan. (You can also transfer to a crock pot at this point if you prefer - see note.)
Simmer for 60-90 minutes or until the beef is tender. Add extra broth halfway if needed to prevent sticking.
If the sauce looks runny, sprinkle in the optional flour and boil for several minutes to thicken up a gravy, stirring regularly to dissolve any lumps.
Serve with rice, potatoes or tortillas.