Add oil to a large skillet and warm to a med-high heat, brown the chunks of beef in the heated oil
After a minute of slightly browning the meat and after the meat releases some of its juices, add the diced onions and green peppers and continue to cook on med-high heat for 3-4 minutes continually flipping the meat to cook evenly
Add the diced tomato, garlic, cumin, salt and pepper and continue to stir the mixture well
Sprinkle flour over the the meat mixture and mix in well
Add 2-3 cups of chicken stock and mix well making sure there are no flour clumps
Heat the mixture while stirring occasionally until it comes to a boil
Make sure the gravy is more of a liquid broth at this stage, cover the skillet and reduce the heat to a simmer, you don't want the gravy at this point to be thick or it will burn and dry out before the meat is tender.
Add extra both and stir occasionally during the simmer process to keep the gravy from becoming thick to soon
Simmer for 1-1/2 hours or until meat is tender to your liking
Serve with your favorite sides like rice and beans or just on a tortilla with some cheese