Prepare the beef by cutting it into even strips (3 inches long and ½ to 1 inch thick). Season it with pepper, fine salt, and half of the garlic.
Over medium-high heat, pour the olive oil into a large skillet and sauté the red, green, and yellow bell peppers until they become soft. Put them on a small plate to set aside.
In the same skillet, brown the beef strips in two batches and put them aside.
Sauté the onion for a few minutes and add the remaining garlic. Stir them for a minute and move them to a separate plate.
Put the beef broth, hot pepper sauce, soy sauce, black pepper, and sugar in the skillet. Slightly heat up and wait for it to deglaze. Then, add the browned beef strips, garlic, and white onion. Let them simmer for 30 minutes.
Add the diced tomatoes, then let it simmer again for 5 minutes.
Mix cornstarch and cold water thoroughly in a bowl, then put it in the skillet. Cook for a couple of minutes and wait for the sauce to thicken.
Add the bell peppers, then let it cook for a minute.
Once the ingredients reach your desired tenderness, it is done.