Bring water, salt, and pepper to boil in a slow cooker set to High. Stir in steel cut oats, cover, and cook 90 minutes.

In a large bowl, mix beef, pork, and onions. Stir into the oat mixture, and reduce heat to Low. Cover, and continue cooking 3 hours, stirring occasionally.

Transfer the mixture to a medium baking pan, and cool until semi-solid. Turn out onto wax paper, and chill 1 hour in the refrigerator, or until firm.

Heat oil in a large, heavy skillet over medium high heat. Cut the refrigerated mixture into thin slices. Cook slices one at a time in the heated oil until evenly brown.