First of all, prepare the filling. To do this, first wash the lentils, then place them in a small saucepan with a generous pinch of salt and cover with water. Let them come to the boil, then simmer very gently, covered, for 40-45 mimutes, or until they are tender.
Meanwhile, heat the oil in a medium-sized frying pan and add the shallot and carrot and cook for 5 minutes, then add the garlic and red pepper, mixing everything together thoroughly and cook for a further 5 minutes or until all the vegetables are softened. Remove from the heat and stir in the peeled tomato, tomato purée and the sun-blush (or mi-cuit) tomatoes. Next, drain the lentils and tip them into a mixing bowl. Add the vegetable mixture and stir to combine everything thoroughly, then leave the filling to cool a little. Now mix the eggs, mace, cayenne, thyme, parsley and sage into the mixture and season generously with salt and freshly milled black pepper.
Now pre-heat the oven to gas mark 4, 350°F (180°C).
For the pastry, put the milk and 2 fl oz (55 ml) water into a small saucepan and add the vegetable fat, cut up into small pieces. Place the pan over a gentle heat and simmer until the fat has dissolved. Sift the flour, mustard, mixed spice, sea salt and nutmeg into a large mixing bowl, and mix in 1 of the egg yolks so that it is evenly distributed. When the fat has completely melted in the liquid, turn up the heat to bring it just up to the boil, and pour it on to the dry ingredients and, using a wooden spoon, mix everything together. Then turn the dough out on to a lightly floured work surface and bring it together with your hands to make a ball.
You have to work quickly now, as it's important that the pies go into the tin whilst this dough is still warm. Take two-thirds of the dough and cut this up into 6 equal parts. Roll each of these into a ball and put 1 into each of the holes in the tin. Using your thumb, quickly press each ball flat on to the base and then up to the top edge. Press the pastry over the rim of the top edge, it should overlap by at least ¼ inch (5 mm). Using a teaspoon, divide the filling between the 6 pies. It will be quite sloppy at this stage, but don't worry, that is normal. Then roll out the remaining pastry and cut out six 3¼ inch (8 cm) rounds; the pastry will be quite thin, so you may need to sprinkle the work surface with a little extra flour. Next, using a pastry brush, paint some of the second egg yolk round the upper edge of the pies and gently press on the lids. Using a small fork, press the rim of each lid against the top of the pie case, make a hole in the top of each pie and glaze with the rest of the yolk.
Now place the muffin tin on the baking sheet and bake the pies for 30 minutes on the middle shelf. After this time, carefully and using oven gloves or a thick cloth, remove the hot pies from the tin and place them directly on to the hot baking sheet; this will make the sides and base crispy.
Bake for a further 20-25 minutes or until the sides and base of the pies are crispy, then leave them to cool on a wire rack.