Wash and dry all utensils and measure ingredients.
Boil 4 cups of water in a medium pot.
Gradually add barley flour while stirring to avoid lumps.
Lower the heat and simmer for 10–15 minutes, stirring occasionally, until it reaches a thin porridge consistency.
Add ½ teaspoon salt and mix well.
Remove from heat and let the mixture cool to room temperature.
Stir in 2 tablespoons of yogurt or sour cream until smooth.
Cover the container loosely and let it ferment at room temperature for 6–12 hours.
Taste the drink; once mildly sour, refrigerate to stop fermentation.
Strain for a smoother texture, chill, and serve cold.