Puerto Iguazú has several good parrillas where Argentine asado is done properly — beef ribs, chorizo, morcilla, and sweetbreads grilled over wood coals, arriving at the table still crackling. Portions are generous; a single mixed grill will defeat most appetites. House wine is cheap and drinkable, usually from Mendoza.
The ritual of asado is taken seriously in Argentina, and a parrilla dinner here is an uncomplicated pleasure after a long day in the park. Lunch service starts late by northern European standards (after 1pm); dinner rarely begins before 8pm.