Keep foods fried in batches crispy until serving by holding them uncovered in a single layer on a wire rack set over a baking sheet in an oven set to 90–100°C / 195–210°F. Fried food piled on paper towels softens underneath in its own steam; covered fried food cannot release its steam. Do not hold it for more than half an hour, because a longer wait makes it dry instead of crisp.
Moisture inside fried food is what ruins its crispness. Food just out of the oil is still very hot inside and continues to release steam. If the steam can escape, the crust stays dry and crisp; if it cannot, it condenses back into the crust and softens it. The underside of fried food resting on paper towels gets wet from the steam and oil the towels hold. Fried pieces piled on top of one another also trap each other’s steam. A lid, foil, or plastic wrap takes this effect to its extreme.
The right way to hold fried food is to let this steam escape. Preheat the oven to 90–100°C / 195–210°F; this temperature keeps the fried food warm without continuing to cook it. Set a wire rack over a baking sheet, let each piece drain over the pot for a few seconds after removing it from the oil, then arrange it in a single layer with space between pieces on the rack. Air circulates beneath the food, too, and steam escapes from all sides. Do not open the oven door unnecessarily; the temperature inside drops each time.
Add salt as soon as the fried food comes out of the oil, while the surface is still hot and lightly oily; salt sprinkled onto a dry surface after holding in the oven will not stick. Holding time is limited. Fried food held in the oven for up to half an hour stays hot and crisp; with a longer wait, the crust hardens, the inside dries out, and thin pieces such as french fries turn into dry sticks. For a large gathering, plan the batches so they are finished no later than half an hour after the first batch goes into the oven.
Not every fried food holds equally well. Breaded chicken, breaded cheese, french fries, and cigar-shaped Turkish pastries hold well in the oven because they have a thick, dry crust. Tempura, vegetables dipped in frying batter, and fried foods with thin batter soften quickly and should be served as soon as they are fried. Fried fish and anchovies also lose their crust if held too long. For fried meat and chicken, holding in the oven also provides a safety benefit: the food does not fall below 60°C / 140°F during this time. Before fried chicken goes into the oven, measure it at its thickest point; its internal temperature should be 74°C / 165°F.
There are a few common holding mistakes. Fried foods are moved to a serving plate too early and the plate is covered; steam that collects on the plate softens the pieces underneath. Different batches are piled on top of one another on the same sheet. Fried food that has started to cool is put in the microwave to warm it again; the microwave wets the crust. When serving, keep sauces separate from the fried food: do not pour sauce under or over it on the plate; serve it in a small bowl on the side. This keeps the food crisp down to the last bite.