In a cast-iron fondue pot, brown the onions and garlic in a small amount of vegetable oil.
Add the fresh or canned tomatoes.
Add the tomato paste.
Season with salt and pepper.
Result: a delicious tomato sauce.
Add the grated cheese and wine.
Melt the mixture over a low heat, stirring well. Be sure to stir the bottom of the pot! Add a dash of pepper.
In the meantime, cook the unpeeled potatoes.