Mix butter, lard, flour, and salt in a food processor until breadcrumb texture forms.
Add lemon juice and water to form a dough, then roll into a rectangle.
Fold the dough into thirds, rotate 90 degrees, repeat folding, and chill for 20 minutes.
Sauté garlic and shallot in garlic oil until soft.
Pulse drained porcini mushrooms in a food processor until they resemble breadcrumbs.
Repeat the pastry rolling and folding process and chill again for 15 minutes.
Simmer all mushrooms with garlic and shallot for 10 minutes before adding thyme and wine.
Reduce the mushroom mixture to a paste, season, and leave to cool.
Sear the seasoned steak pieces in a hot pan until browned and allow to cool.
Wrap each cooled steak piece tightly in a slice of ham.
Perform a final roll and fold of the pastry and chill for 15 minutes.
Preheat the oven to 200°C.
Roll pastry to a 30cm x 45cm rectangle and cut into six 15cm x 15cm squares.
Spread mushroom paste on pastry, place beef in the center, and wrap tightly.
Brush with egg wash, score the tops, and bake for 25 minutes until golden.