Wash the rice first and then place in a saucepan together with 3 cups water and add salt and cook for about 15 minutes, until it softens. And then reduce the heat.
In a bowl, beat the egg, put plain yogurt, flour, and 1 cup of water and mix them well.
Add the yogurt mixture inside the saucepan and stir slowly to let the rice and yogurt mixture mix well. Stir continuously until it comes to boil and then cook for 10 minutes.
In a separate pan, melt the butter or margarine and add the mint, stir a couple of times and let it sizzle then remove from heat and slowly sprinkle over the soup.