Not really exotic, but we used to grow Tarbes beans in France. They grow on the vine, and are left there until they dry up in late summer. Then you pod them. They're a bit like butter beans but the skins are much softer and they're much more tender. Good for casseroles. and very expensive. Do you think they could be grown in 'northern climes'? I realise the soil is relevant too.
Yes, you really need a greenhouse. However, if you have patio doors facing south, it might be possible to grow them in a large pot. I grow tomatoes on my kitchen windowsill, which faces south. It's also easy to give them the care they need.