Peel and grate the onions, finely crush the garlic cloves in the salt. Cut the tomatoes into quarters, cook them with the garlic until soft and pass them through a sieve while hot.
Mix the flavor ingredients and heat until the sugar has dissolved. Then add the tomato paste, season to taste and boil down in an open saucepan over medium heat for about 1 to 2 hours until thick.
Fill into bottles or glasses while boiling and seal airtight.