Parboil the brats for 10 minutes, brown in the broiler, and serve the next day in a Nesco floating in beer and onions. PUrists will sneer at pre cooking but it's a necessity in this case. Works for us. Use Johnsonville if you can get them. They have a Stadium brat that is already pre cooked and very tasty.
Foods such as orange juice and milk are definitely enriched with vitamin D, but these foods are not intended to be good sources of Vitamin D, they are merely foods designed to prevent the most obvious vitamin deficiencies, particularly in children.
Of course, the orange is obviously an excellent source of vitamin C as it provides 117 percent of the Daily Value for C (any food that provides 20 percent or more Daily Value is considered an excellent source).