Vietnamese Meat Pies | Pate Chaud

Preheat the oven at 350 degrees.
In a pan on medium high heat, add oil and butter and sauté onions with a pinch of salt. After a minute, reduce the heat to low and saute for 30 minutes until the onions soften and start to caramelize. Set aside.
Combine all ingredients of the filling together, add the caramelized onions.
Separate egg white and egg yolk, keeping both. You will use egg white to seal the dough and egg yolk to brush the top of the square to give it that beautiful golden color after baking.
Mix egg yolks with milk and set aside.
Unfold the pastry sheet. Cut each sheet into 12 squares to get a total of 48 squares. Separate the squares.
Brush the edges with egg white. Add 2 Tbsp of filling into 24 square pieces. Place remaining 24 square pieces on top of the ones with the filling. Gently press them together to seal. For decorative purposes, you can use a fork and press down on the edges otherwise it’s not necessary. Brush the top of the pastry with egg yolk/milk mix.
Line a cookie sheet with parchment paper and place your pastries on top.
Bake in the oven for 40 minutes. Carefully paying attention towards the end as you want to make sure its a nice golden brown and make sure they don't burn. If it's too light of a brown then that means it's not ready yet.