"Pulperias" are traditional establishments in Galicia where the main fare is basically octopus and regional products. They are very common in rural areas and typical rest stops for pilgrims.
On the outskirts of the city's historic district is Os Concheiros. For two people, order a plate of "pulpo" (octopus, 8?), which you can accompany with half an order of "queso de tetilla" (soft cheese, 2€), an order of "Pimientos de Padrón" (red peppers, 3,50€), an order of "zorza" (spicy pork, 4€) and an order of French fries (2.50€). The house white wine, served in traditional ceramic cups, is very good (3.50€). Lunch will run you around 10-12€ per person.