Season the beef generously with salt and pepper. In a large dutch oven brown cubed round steaks on all sides in a hot pan with vegetable oil. Brown the meat in batches for about 5 minutes per batch until all the meat is browned—do not crowd the pot. Add more oil as needed. Transfer the browned meat to a plate.
If using fresh onion, add it to the pan with some additional oil and saute until tender. Add 1 cup of water to the pan (be careful because it may spit at you) and deglaze the pan, scraping up all the brown bits. Add remaining water and browned beef, add more if necessary to almost cover the meat.
Stir in beef base (Better Than Bouillon) and dehydrated onions, if using.
Cover the pan with a tight-fitting lid and roast in a preheated 350º oven for about 1 hour or until the meat is fork-tender.
To make the gravy, mix flour with 3 tablespoons water and gradually whisk into the dutch oven on the stove over medium heat, stirring until it thickens. You may need to add more of the flour mixture or more water to get the desired consistency. Add salt and pepper to taste.
Serve with over egg noodles prepared according to package directions. Top with sour cream, optional.