Cut up lots of rhubarb, maybe 6 to 8 cups, into less than 1 inch size chunks. Add 1 cup white sugar, 1/4 cup flour and a 1 teaspoon of cinnamon. Mix well and let it macerate while making the pastry.
Pastry (recipe from the Tenderflake Lard package):
Mix 5 1/2 cups flour and 2 teaspoons salt in the bowl of a mixer. Cube a chilled 1 pound package of lard. In a glass measuring cup put 1 egg and 1 tablespoon of either lemon juice or vinegar, add cold water to make one cup and mix with a fork. Mix the lard into the flour until reduced to smallish pieces then add the liquid gradually while the mixer is running. When it forms a big clump, stop.
Roll out a largish disk of pastry on a well floured marble slab to create a large rough circle. Put this bottom pastry into the pie dish and dump in the fruit. Pull up the pastry around the fruit. Roll out a small centre piece and put on top. Brush with either orange juice (shown) or cream or an egg wash, then sprinkle liberally with white sugar.
Put the pie dish on a baking sheet in case of boil overs. Bake in a pre-heated 450F oven for 10 minutes to brown the pastry, then reduce heat to 350F and bake another 50 minutes until the juice is bubbling and fruit is cooked. Cool before serving.