I've found a recipe for a lemon tart: http://www.bbcgoodfood.com/recipes/380616/greggs-tangy-lemon-tart
Everything looks fine to me and I get what to do exactly, but I don't understand the part that says:
Line the tart with foil and fill with rice or dried beans. Bake for 10 mins, then discard the foil, and bake for another 20 mins until biscuity.
I have got two closely related questions:
What is the purpose of this step? What would happen if I omitted it and baked straight for 30 minutes?
What type of foil should I use? I suppose it's not the plastic one since it would not survive the baking temperature of 160C. Or would it?