After inviting the disciples to see and touch him, Jesus asks whether they have food. They give him a piece of broiled fish, and he eats it in their presence.
The detail combines an everyday food with Luke's deliberate insistence that the risen Jesus is not merely a disembodied apparition.
Fish was a common food around Galilee and elsewhere in the region, obtained fresh, dried, salted, or cooked. Broiling fish required no exotic preparation and fits the ordinary food world of Jesus' followers.
Luke's emphasis is not on a symbolic menu. The disciples had thought they were seeing a spirit; Jesus' handling and eating of food reinforces the physical continuity already expressed by 'flesh and bones.'
The ordinary character of the meal detail is precisely what gives it force. Resurrection enters the disciples' familiar material world: hands and feet can be seen, a body can be touched, and food can be eaten.
Luke thereby presents resurrection as bodily life, not merely the persistence of Jesus' memory or an encounter with an incorporeal ghost.