Preparations: Preheat the oven to 325 degrees Fahrenheit and grease the tart pans
Cut the lard
Use a sifter to sift the flour into a large bowl
Work the lard and butter into the flour with the tips of your fingers, until the mixture has the appearance of coarse breadcrumbs
Continue kneading, adding the hot water
Roll the dough into a large ball, cover with wax paper and refrigerate while preparing the custard filling
Lightly beat the eggs, taking care not to produce any air bubbles
Stir in the milk and the sugar
Add the yellow food color if using
On a large, lightly floured surface, roll out the dough until it is very thin (about 1/8-inch or 3 to 4 mm thick)
Cut the dough in half before rolling out if needed
Use a pastry cutter to cut out 18 circles that are 3-inches in diameter
Fit the circles into the tart shells
Pour the filling into the shells
Bake until the custard is cooked and a knife inserted in the middle comes out clean (about 35 minute)
Cool