1. In a pressure cooker, fry the onion in vegetable oil until golden. Add the lamb cubes and stir for few minutes until half done.
2. Add the tomato sauce, chopped tomatoes, chicken stock cube and 2 cups of water. Close the cooker and cook meat on medium heat for almost 30 minutes until it is done.
3. Remove pressure cooker from heat and wait until all steam escapes before opening.
4. Open the cooker, add the Quaker oat meal, white pepper, black pepper, salt and water if needed. Put the cooker back on low heat while continuing to stir, until the oatmeal is cooked, for about 20 minutes.