Wash and quarter the tomatoes and cook them in a small pan with a little water for 10 minutes until soft, then press them through a sieve (skip this if using ready-made passata).
In a separate pan, cook the flour in the lard over medium heat for 2-3 minutes, stirring constantly, until you have a pale roux.
Pour the water onto the roux, stir until smooth, season with salt and bring to the boil.
In a separate small pan, cook the rice in lightly salted water for 12-15 minutes until tender, then drain.
Stir the tomato purée into the hot soup, season with sugar and salt and bring back to the boil.
Add the drained rice and heat through together for 2-3 minutes.
Meanwhile, cube the roll and toast it in a dry frying pan or in a little fat until golden.
Taste the soup before serving, add more salt if needed, and serve with the croutons.
Based on: A jó házikonyha (a classic Hungarian cookbook), modernised. Calories and protein are estimated.