The Turkish name may derive from Arabic: راحة الحلقم rahat al-hulkum: contentment of the gullet.
Originally published here:
2 cups sugar.
4 tablespoons cornstarch.
1 cup water.
1/2 teaspoon cream of tartar.
2 tablespoon rosewater (available at Middle Eastern stores).
1/2 cup chopped pistachios, walnuts, or almonds.
Confectioner's sugar for dusting.
Mix sugar, cornstarch and cream of tartar with the water and boil for five minutes, stirring the while. Remove from heat and add rosewater and chopped nuts. Apply a little cooking oil to a rectangular pyrex dish (or use non-stick cooking spray) and pour in mixture to a depth of an inch. When cool, cut into rectangles and roll each piece in powdered sugar.
Store at room temperature in airtight container.
Fruit juice may be used in lieu of plain water - strained orange juice or clear apple juice is excellent, and a lemon may be squeezed in for tanginess. Food colouring as deemed appropriate can be added, and some people roll it in coconut shreds or crushed nuts.
Note that it can also be made with orange essence, or even orange blossom water (moit ez zaher), in lieu of the rosewater (moit el ward). Rosewater is traditional, but not essential.