1 cup flour (spelt, oat, barley or millet)
1 1/3 cup sugar
½ cup boza with sugar (bought or from previous making) or homemade ferment
2 liters water
For the homemade ferment: ½ cup water, 1 teaspoon sugar, 1 tablespoon grilled flour
For the homemade ferment, mix the ingredients until you get a smooth paste, transfer to a glass jar and cover with a cotton cloth. Leave to room temperature for 2-3 days to activate the fermentation. Shake the jar several times per day.
To make the Boza, dry-roast the flour in a skillet. Stir constantly so as not to burn it. Then let cool and transfer to a deep pan. Dilute with a little cold water to make a smooth puree. Gradually, pour in the remaining water. If lumpy, blend. Finally, add the sugar and heat the pan on medium heat until boiling point.
Count 6 minutes of cooking from boiling, stirring all the time to prevent the Boza sticking to the bottom of the pan. Then remove from heat. Cool to 36-38°C and add the glass of Boza with sugar or the homemade ferment.
Tranfer the Boza in glass bottles or jars, seal and leave in a warm place to ferment at its rhythm. Shake several times per day. Bulgarian drink is ready in about 24-36 hours. When ready, store it in the fridge and enjoy it cold at breakfast or with the afternoon snack with butter croissants and other sweet or salty puff pastries. Consume quickly, up to 4 days. Reserve ½ cup to make a new dose.