The French is topinambour, in English it used to be the Jerusalem artichoke but stores are now calling it sunchoke or sunroot, maybe because it is neither from Jerusalem nor a member of the artichoke family. It is a tuber native of North America and can be prepared basically like potatoes. It does have a more sophisticated taste though, pretty close to artichoke.
I prepared them very simply so the subtle taste is not overwhelmed by strong spices. First, peel them and slice them. Slices about 2mm thick, then transfer them right away in an oven roasting disk that has a lid with 2 tbsps olive oil, a small piece of butter and 1/4 of a finely chopped sweet onion, salt and pepper. Cover and cook for about 30 minutes at 330. There is no need to add water or milk. The starch of the tubers will create a nice creamy like effect. You could sprinkle a bit of grated cheese but I did not. The bottom layer browned nicely so turn the gratin over when you serve.
In Europe, topinambour are still considered a war vegetable like rutabagas and a lot of people who were children at that time won’t eat them. During the few years when food coupons were in effect, many grew potatoes, rutabagas and topinambours in the basement and this is basically all the vegetables they ate. Meat allowances were a mere few ounces per week so most meals were a variation on the root vegetable theme. These vegetables had a very low profile there as a result and it is only recently that they are again featured on restaurants menus.
If you are looking for “sunchokes” in Victoria, BC, the place to go is the aptly named produce market “The Root Cellar”. They have them right now.