Slatko is a type of Serbian fruit preserve. The term itself is Serbo-Croatian and means "sweet." Slatko can be made out of nearly any fruit, though plum is one of the most common choices. Strawberries, cherries, and blueberries also work well. Slatko is traditionally served to guests either by the spoonful or with coffee after a meal.
Similar to any type of fruit preserves, slatko has a consistency that lies between jam and syrup. It can be used as either a topping for pancakes or waffles or a spread for breads. Unlike jam and most syrups, but like many preserves, slatko contains whole pieces of fruit.
Sugar, citric acid or lemon juice, and the fruit of choice are the primary ingredients in this preserve. Water is also essential. If plums are used, walnuts are often included as well — this combination is considered an aphrodisiac.
Normally, near equal amounts of sugar and fruit are added to slatko. If citric acid is used, it is dissolved in water and then the fruit is soaked in the mixture for about an hour. When lemon juice is used, the juice is added later in the cooking process and the fruit is not usually soaked prior to cooking.
To cook, water is boiled with sugar until a syrupy mixture forms. Then, the fruit is added and the mixture continues to boil. Usually foam will form on the top of the mixture and must be skimmed off and disposed of. If lemon juice is used, it is included while the fruit boils.
Fruit that needs to be skinned and pitted or cored, as in the case of plums, will normally be boiled prior to its inclusion in the syrup. The boiling loosens the skin so the fruit may be easily peeled. After boiling, the skins and pits or seeds are removed from the fruit.
Once the fruit is boiled, the heat is reduced and the dish is allowed to simmer. Finally, the pan is removed from the heat and covered so the fruit mixture can cool over night. Once cool, the slatko is placed into canning jars and sealed. Properly canned slatko will keep for months.
Although generally the amount of fruit in slatko equals the amount of sugar used, this is not always the case. Sweeter fruits require less sugar than more tart fruits. Additionally, the tastes of the cook may determine how much sugar is added, and thus how sweet the finished slatko is.