Simmer liver and onions in stock for 30-40 minutes. Put oatmeal in a heavy pan over heat or under the grill, and toast until nicely browned. When the meat is cooked, remove from pan, keeping liquid. Mince liver and onions, add oatmeal, suet, salt and pepper. Moisten with sufficient liquid to give a softish consistency, put in a greased pudding basin and cover with a double lid of foil, and steam for 3 hours.

Now, you probably don't have a pudding basin (I'm not sure what one is).

From "The Highlander's Cookbook, " by Sheila MacNiven Cameron, here is an alternate method:

Turn into a greased Pyrex bowl. Cover with two or three layers of foil. Steam on a rack in a pan of boiling water for two hours, adding more boiling water as it boils away.