Lao food is built around sticky rice, fresh herbs, grilled meats and river fish, with fermented fish sauce and padaek (a fermented fish paste) in many dishes. Local specialities in the guides include or lam, a mild herbal stew usually made with pork, and Luang Prabang-style khao soi. Almost every traditional dish contains meat, fish or fish sauce, so strict vegetarians, Jain travellers and vegans should expect to ask clearly and repeat the request.
In practice, the easiest meals for Indian vegetarians are the vegetarian stalls at the night market food alley (one stall is labelled vegetarian and another vegan, according to Wikivoyage, with a note on hygiene), fried rice or noodles cooked without egg or fish sauce on request, fruit, and Indian restaurants. We found one Indian-run restaurant, Nisha, that a travel guide describes as strong on vegetarian and vegan dishes, though it also serves halal meat, so it is not pure veg. We did not find a verified pure vegetarian or Jain restaurant in Luang Prabang, and have tagged none. Ask your hotel in advance for meals with no meat, fish, fish sauce or egg, and carry dry snacks for day trips.