Heat the olive oil and add the diced potatoes and onions, stirring to coat. Cook until lightly browned, stirring periodically.
Add the sausage and stir to break up. Cook until the sausage is cooked through, stirring with the potatoes. Add the garlic and cook a few more minutes, then add the garlic salt (or just salt) and pepper, sugar and the canned tomatoes (or diced fresh tomatoes, but it's winter here).
Cook a few more minutes until most of the tomato juices have evaporated.