Preheat the oven to 200°C/Gas Mark 6. Grease the holes of the Lakeland Mini Morsel tin with a little melted butter.
Put the flour and salt into a large mixing bowl. Rub in the butter and white vegetable fat with your fingertips until the mixture looks just like breadcrumbs. Add just enough chilled water to make a soft (not sticky) dough. Bring the mixture together with your hands and knead lightly for a few seconds until smooth.
Roll out the dough thinly on a lightly floured surface. Cut out 24 circles using a 6cm (2¼in) round cutter, re-rolling the dough as needed. Use the pastry pusher to gently push the pastry into the holes. Prick the bases with a fork, then put a small piece of scrunched foil into each one.
Bake for 15-18 minutes, until the pastry cases are pale golden brown. Allow to cool, then remove the foil.
For the filling, mix together the cream cheese, condensed milk, lime zest and lime juice. Spoon into the tarts and top with the raspberries. Decorate with mint leaves, if desired, sprinkle with a little icing sugar and serve.