In a large mixing bowl combine the semolina, sugar, baking powder and baking soda, mixing well.
Stir in the yogurt.
Add the milk and orange rind, mixing until well combined.
Lightly grease a 9x14-inch baking pan with the tahini.
Pour in the batter and set aside for thirty minutes.
Bake at 350 degrees for twenty to thirty minutes, or until a golden brown.
Cut into squares.
Prepare the syrup by boiling together the sugar and water for five minutes or until the sugar is dissolved.
Add the lemon juice and simmer for another ten minutes.
Pour the syrup over the hot cake and leave at room temperature until the syrup is absorbed.