Ingredients

• 2 fresh Limes, finely grated rind and juice
• 1 x 14oz (400g) tin of sweetened, condensed milk
• 3 tsp cold water or chilled fresh orange juice 
• 1 egg yolk
• 2 tablespoons sugar
• 1.5 cups all-purpose flour (approx. 180g)
• 3 medium Eggs, separated
• 1 stick (1/2 cup - 110g) cold unsalted butter, cut into pieces

Instructions

1. Into a large bowl, sift together flour, sugar and a pinch of salt. Cut in butter with two knives or fingertips until mixture resembles coarse meal.
2. Sprinkle cold liquid over flour mixture and toss with a fork until a dough forms, adding additional liquid if necessary, being careful not to moisten dough too much. Form dough into a ball and flatten into a disk. Wrap dough in plastic wrap and chill 1 hour.
3. Bake Blind: 15 minutes (lined with foil and beans) and then 10-15 minutes without lining
4. Brush pastry with egg white when baked.
5. A very warm mixing bowl is needed, so fill one with almost boiling water and leave for three or four minutes, then pour off the water and dry.
6. Put the egg yolks in the bowl and beat at high speed. Dribble in the condensed milk a little at a time, beating constantly, then fold in the rind and juice of the limes.
7. In a separate clean bowl, whisk the egg whites until stiff.
8. Fold the whites into the condensed milk mix and then spread evenly over the pre-baked base.
9. Bake in a pre-heated oven at 180C (350F, gas mark 4) for 15 minutes. Remove and leave to set and go cold.