The defining Québec City poutine chain, founded in 1969 by Ashton Leblond — who is credited with inventing the poutine format as it's now understood (fries, cheese curds, gravy). Chez Ashton has become something between a regional institution and a fast-food chain, with locations across the greater Québec City area. The quality is consistent and the poutine is legitimately good: proper fresh cheese curds, thick gravy applied generously, and fries cooked to order.
For visitors who want to understand poutine without navigating fine-dining interpretations of it, Chez Ashton is the most honest option in the city. Open late; busy on weekend nights. The locations outside the Old City walls (notably the one near the Parliament Building) are cheaper and less crowded than any tourism-adjacent alternative.