In a saucepan, combine the sugar and water over medium heat. Stir until the sugar dissolves, then bring the mixture to a boil.

Reduce the heat to low and simmer the mixture for 20-30 minutes, stirring occasionally, until it thickens.

In a separate bowl, mix together the cornstarch and 1/2 cup of water until smooth.

Add the cornstarch mixture to the saucepan and stir well.

Add the lemon juice and rosewater to the mixture and stir again.

Add food coloring (if using) and stir until the desired color is achieved.

Pour the mixture into a 9-inch square pan lined with parchment paper.

Let the mixture cool to room temperature, then refrigerate for 1-2 hours, until firm.

Use a sharp knife to cut the Lokum into small squares.

Dust the squares with confectioners' sugar before serving.