Foods & cuts · Onion

Whole onion

Forty-five to fifty minutes whole, thirty-five to forty halved. The longest cook of any common grilled vegetable, and the clearest demonstration that cutting a vegetable changes the cook rather than shortening it.

What it is

Form: Whole vegetable
Typical weight: 150–250 g
Typical thickness: 60–80 mm
Cut: Not a cut of anything

Why it behaves as it does

North Dakota State gives forty-five to fifty minutes whole and thirty-five to forty halved. The interesting part is that halving an onion does not halve the time: the heat still has to travel through most of the same depth, and what actually changes is that a cut face can now colour. This is the same lesson the corn husk teaches — a preparation choice changes the mechanism, not just the duration.

When is it done?

Food-safety endpoint

BBQHQ holds no food-safety rule for this food. We are not showing you another jurisdiction’s figure in its place — check your national food-safety authority.

Texture endpoint — how you actually know

Yielding all the way to the centre

A skewer passes through the middle without resistance. Forty-five minutes is not an error: an onion is the slowest common vegetable on a grill.

How long it takes

Whole onion, grilled

Estimated cooking window

45 min–50 min

Low confidence

Why this is a range, not a number

Cookers hold temperature imperfectly
Individual animals and pieces differ

Cook to the endpoint, not to the clock. The window tells you when to start checking.

What this rests on

BBQHQ publishes a window for this cook.

Observations: 1
Documents: 1
Publishers timing this cook: 1

North Dakota State University Extension

Why confidence is not higher

At least one source does not state the cooker temperature.

How the sources were combined

ONE PUBLISHER, STATED AS A TOTAL. North Dakota State gives 45–50 minutes and no grill temperature, saying only that the time depends on the heat of the grill. BBQHQ publishes it as it stands and does not manufacture a second voice for it.

What makes the window as wide as it is

Cookers hold temperature imperfectly
Individual animals and pieces differ

When it goes wrong

Burnt outside, underdone inside: Vegetables charred outside and hard in the middle — 2 distinguishable causes.

Afterwards

Cooling, keeping and reheating what is left is general guidance for barbecue leftovers. Neither UK authority publishes anything specific to whole onion, and BBQHQ does not invent a distinction they do not make.