Cook the onions in the same pan until soft and translucent, about 5-7 minutes. Add the reserved 3 tablespoons of seasoned flour, stir to combine, and cook for 1 minute. Add the beef broth and the milk, increase the heat, stirring constantly to prevent lumps. Bring to a boil and deglaze the bottom of the pan, loosening any browned bits. Reduce the heat to low, nestle the chicken fried steak patties in the gravy, cover, and simmer for 15-20 minutes. Taste the gravy and add salt and pepper according to taste.