Partially freeze the steak for 15-20 minutes (this will make it easier to cut). Cut the steak into thin strips.
Wipe the mushrooms with a damp cloth and cut into slices to make 1 cup.
Remove the stems and seeds from the bell peppers and cut into thin strips.
Peel and chop the onion and garlic clove.
Drain the can of baby corn and soak in cold water for 15-20 minutes then rinse under cold water. If you use fresh baby corn then just wash with cold water and drain.
Combine the soy sauce with the beef broth. Set aside.
Combine the cornstarch with the water and set aside.
Heat up 2 tablespoons of oil or margarine a large skillet or frying pan with medium-high heat. Brown the meat, turning over once.
Turn the heat down to medium. Push the meat to the side and add the onion and garlic to the frying pan.
Add the mushrooms and the baby corn. Cook for 1 minute.
Add the soy sauce and beef broth. Stir in the sugar. Bring to a boil, then reduce the heat, cover and simmer until the meat is tender (this will take around 25-30 minutes).
Add the peppers and stewed tomatoes. Cover and cook for another 5-10 minutes.
Bring to a boil and stir in the cornstarch and water mixture. Cook, stirring constantly for 4-5 minutes until the food is thick and bubbling. Taste and add salt and pepper if desired. Serve over cooked rice.