Heat lard in a large microwave-safe bowl until melted, 30 seconds to 1 minute. Stir in boiling water. Combine flour and salt in a large bowl. Make a well in the center and pour in lard mixture. Mix with a wooden spoon until a smooth, slightly sticky ball of dough forms. Dust a flat work surface with flour and knead dough for 2 minutes. Roll out 3/4 of the dough into a 1/3-inch thick circle. Press over the bottom and all the way up the sides of a 10-inch springform pan. Roll out remaining dough into a 1/3-inch thick circle for the top of the pie. Freeze pie crust base and top until firm, about 10 minutes. Meanwhile, combine ground sausage, ground pork, pork tenderloin, onion, parsley, pepper, thyme, mixed herbs, and curry powder in a large bowl. Mix into a paste. Preheat the oven to 375 degrees F (190 degrees C). Line the bottom and sides of the pastry crust with streaky bacon. Press in 1/2 of the pork mixture. Cover with 3 to 4 slices of streaky bacon. Press in remaining pork mixture; arrange remaining streaky bacon on top. Brush pastry rim with milk and add the top crust. Pinch the edges together to seal. Brush the top with milk and cut 2 slits in the top of the pie. Bake pie in the preheated oven for 1 hour. Reduce the oven temperature to 300 degrees F (150 degrees C) and bake until an instant-read thermometer inserted into the center reads at least 160 degrees F (71 degrees C), about 1 hour more. Cool pie completely before removing from the pan.