Is It Okay to Start Cooking Before the Oven Is Fully Preheated?

This summer has been a whirlwind, and when I’m roasting vegetables for meals, I’ve often tossed them in the oven before it’s completely heated to save time. But while I was in the shower the other day (where all my best ideas come from), I had a thought: maybe this isn’t such a good idea. Could it mess up the cooking time and result in unevenly cooked food? Or is it fine for simple things like veggies but risky for more delicate dishes like meat?

So, what’s the verdict? According to chef and restaurateur Claudia Sidoti, 'Preheating is generally only essential for foods that require a specific temperature right from the start.'

Which foods are those? Claudia Sidoti and Ian Rynecki, executive chef at Pippin Hill Farm & Vineyards in Charlottesville, Virginia, break it down for us.

Vegetables

Let’s start with the food that sparked this whole discussion: vegetables. While precise oven temperature isn’t as crucial for veggies as it is for some other dishes (we’ll get into those shortly), it’s still a smart move to fully preheat your oven before popping in your sheet of veggies, says Rynecki. 'Other chefs might have different opinions,' he adds, 'but this is my advice if you want the best flavor.'

He even takes it further. 'I’d recommend putting the sheet pan in the oven while it’s preheating,' says Rynecki. Then, once the oven reaches the right temperature, 'take out the pan, add your veggies, and listen for that sizzle.' The hot pan quickly raises the temperature of the veggies, which helps them caramelize better. And that caramelization? That’s where the flavor is, according to Rynecki. So, while my trick of putting veggies in before the oven is fully heated might save time, Rynecki points out that it comes at the expense of flavor.

Egg-Based Dishes

Any dish involving eggs—like stratas, frittatas, quiches, and more—requires a preheated oven, says Rynecki. Just as you wouldn’t start boiling eggs in cold water, you wouldn’t want to bake an egg dish in a cold oven. The reason egg-based dishes need a hot start is simple: 'A low temperature at the beginning won’t allow them to puff up properly,' says Rynecki. A baked egg dish without that fluff? No way.

Bread

Bread is another example of a food that demands a preheated oven. When you place bread dough in a preheated oven, that instant burst of heat helps the yeast complete its rising process, according to Rynecki. If you put the dough in a cold oven that gradually warms up, the bread will still be edible, but it won’t have the same depth of flavor. A fully preheated oven delivers that 'final 5 percent' that can turn good bread into great bread.

Generally speaking, any recipe that requires rising—such as bread, biscuits, or egg dishes—needs a fully preheated oven, says Rynecki. So, if you’re making one of these dishes, patience is key.

Pastries

All types of pastries should only go into the oven when it’s at the exact temperature required, says Rynecki. These delicate items depend on an initial burst of heat to cook evenly and rise or puff properly.

Take biscuits, for example. If you put a tray of biscuit dough into an oven that isn’t fully heated, the bottoms will burn before the tops have fully cooked because the heat rises too slowly from the bottom. A burnt yet gooey biscuit? That sounds both awful and perplexing, according to Rynecki.

Take cookies, for example. 'If you place cookies in a cold oven, they’ll come out flat and dry,' says Sidoti. That sounds almost worse than ruined biscuits.

Meats

Generally speaking, roasts that cook at low temperatures for extended periods (like 310 degrees or lower) don’t require preheating, according to Rynecki. The process is more about 'low and slow' cooking than an immediate blast of heat. That said, preheating won’t hurt either. 'It won’t change much,' he adds, 'since the cook time is long and the oven stays at a relatively low temperature.'

However, when it comes to braised meats, it’s a different story. Placing the meat in the oven before turning it on allows the heat to rise gradually, helping the meat fibers break down more evenly than if you start with a preheated oven, explains Rynecki.