For a vegetarian, what would be the best diet to get protein from non-animal products, and is it recommended for HIV patients?
A vegetarian diet can be quite appropriate for HIV patients if it is done properly. The sources of protein will vary depending on what type of vegetarian you are. If you are a lacto-ovo vegetarian (you eat dairy products and eggs), then protein is not usually a problem. If you are a strict vegan who does not eat any animal-related products, you will have to consider combining some foods to get the complete protein you need or including soyfoods where you can.
The specific recommendations for you will depend on a profile of your risk factors for nutrition-related and other disease problems. So, the best recommendation I can make is for you to visit a dietitian to go over the options that may be best for you. The dietitian will also be able to point you in the direction of some very good resources that may apply specifically to your situation.