Roast potatoes are the staple of the British Christmas meal. Potatoes are also one of the lowest-carbon sources of starchy foods – one study last year found a dietary shift from rice to potatoes in China could reduce its staple crop emissions by 17-25% by 2030. They also happen to be produced locally to where I live in Scotland, so as long as I choose options grown nearby, they are likely to have relatively low transport emissions.