Crumble the bread into a bowl; add the milk& leave to soak for 30 minutes.
Meanwhile, put 15g (1/2 oz) of the butter, flour and stock into a saucepan. Heat, whisking continuously until the sauce thickens, boils and is smooth.
Add the tomatoes, sugar and thyme. Season to taste and simmer, covered, for 30 minutes.
Put the onion and the mince in a bowl and add the soaked bread together with any remaining milk and paprika. Season to taste. Using floured hands, shape the mixture into 16 balls.
Heat the oil and remaining butter in a frying pan, add the meat balls, a few at a time and fry until browned all over.
Place the meat balls in a single layer in a shallow ovenproof dish and pour over the sauce. Cover and bake at 180˚C (350˚F) mark 4 for about 30 minutes.
