From the vegetarian pilgrims I met and from what I saw on the route back then, it is feasible to follow a vegetarian/vegan diet, although it may take more effort to plan and navigate than more popular routes, esp. the Camino Francés. Restaurants seemed to have one or two vegetarian options or were able to modify dishes, such as leaving out tuna on salads. If you’re not proficient in Spanish, I’d recommend learning some keywords and phrases to communicate that you follow a vegetarian/vegan diet and how to ask for menu modifications. Also, be familiar with some basic Spanish dishes and their ingredients to help you navigate menus. Buying your own food and ingredients from local markets is also a good option, for anyone, regardless of diet. The alberque in Sambalismo (after Borres) served vegetarian meals: www.gronze.com/asturias/samblismo/albergue-samblismo. Lastly, if you’re a Facebook user, I’d recommend joining this group for more info and support: Vegetarians and Vegans on the Camino: facebook.com/groups/202518663576649. Hope this helps. Bueno Camino!