Potato
Potatis
96°C
Cook to this all the way through
The one vegetable worth a thermometer. Probe for softness.
On the grill
Unlike most vegetables, a whole potato benefits from a probe: the centre needs to reach close to 96 °C before the starch has properly softened.
Indirect heat for the bulk of the cook, wrapped in foil or not depending on whether you want a crisp skin, then finish direct if you want char on the outside.