The waterfront near the fishing harbour has several no-frills restaurants serving what Safi does better than almost anywhere in Morocco: grilled sardines. The sardine boats bring the catch in daily, and on a good day you can eat fish that were in the sea that morning, charcoal-grilled and served with flatbread, olives, and harissa.
Restaurant des Sardines is one of the more reliable spots, with outdoor tables overlooking the harbour and straightforward pricing chalked on a board. Order the sardines, add a bowl of fish soup if it's available, and you have a very good meal for very little money.