This is a favorite British recipe that can be served for breakfast or enjoyed as a sweet snack at teatime. It's nicely crisped and browned, with a soft jam-filled center. Marmalade or lemon curd can also be used for the fillings.
Preheat oven to 400° or at mark 6. Grease a large ovenproof baking dish; set aside.
To make the pastry, mix the flour and suet (or oil) together in a bowl, and mix in just sufficient cold water to make a firm (but not sticky) dough.
Roll out the pastry to 1/4-inch thickness on a lightly floured surface to form a strip 8 to 10 inches long. Spread a good layer of jam (warmed, if necessary) over the pastry to within 1/2 to 1 inch of the edges. Moisten the edges of the pastry, roll up carefully from a long side. Pinch the top edge to form a seal. Seal the two ends well too, to prevent jam filling from spilling out during baking.
Place the jam roll in the baking dish and bake at 400° for about 30 minutes or until golden brown.
Serve hot or cold. To serve, cut in slices, and serve with custard.
NOTE: Alternatively, the mixture can be rolled up in a floured pudding cloth and steamed for about 2 1/2 to 3 hours to make Jam Roly Poly.