Lemon Shortbread Cookies

Dough

• 2 lemons
• 4 oz sugar
• 8 oz unsalted butter, chilled, cut into pieces
• 12 oz all-purpose flour, plus extra to dust
• ¼ tsp salt

Icing

• 9 oz confectioners sugar
• 2 - 4 drops food coloring, pink, to taste