My friend is lives in France and can't find Trex in the supermarket. I can't think of an equivalent French product. Do you have any suggestions?
Unfortunately vegetable shortening (such as Trex/Crisco) is hard to find in France. We suspect this may be as it is more traditional to buy patisserie in France than to make your own. There is a similar product product called Vegetaline available in some stores in France, though this is made from coconut oil and mostly used for deep fat frying. You may be able to find Crisco in some supermarkets where there is a high American ex-pat population. It will not be in the chiller section but in the main aisles, as it can be stored at room temperature until it is opened. You can also buy Crisco on-line from a website in France called My American Market.
In most recipes you can substitute butter for the vegetable shortening. For greasing pans then you should be able to use a flavourless vegetable oil, such as sunflower oil.