Make the suet pastry: using self raising flour rub in the suet until the mixture resembles breadcrumbs then add the salt and pepper. Add just enough water to make a stiff dough (add a little at a time). Roll out on a floured piece of greaseproof paper (about 40x40 cm) to make an oblong.
Lay the bacon over the pastry leaving 2cm clear around the edge. Cover the bacon with the sliced onion, and sprinkle the stock cube over the top.
Use a little water to wet around the edge of the pastry, and roll up like a Swiss roll. Use the paper to push it over. Finish with the seam at the bottom, and loosely cover with the paper. Use the paper to transfer to a baking tray.
Bake in the preheated oven for 40 minutes, uncovering for the last 10 minutes, until the pastry is golden brown, the onions are tender and the bacon is no longer pink. Remove from the oven, slice and serve.
Serve with onion gravy or I like a mustard sauce. This will serve 4 with a large appetite or 6 normal.