Step 1

Cut beef into 1-inch pieces (2.5-centimeters) and season with salt and black pepper.

Step 2

Heat oil in a skillet/frying pan and brown half of the beef pieces on high heat on all sides, about 1-2 minutes max! Transfer onto a plate lined with a paper kitchen towel and repeat with the other half. Set aside.

Step 3

Preheat oven to 400 Fahrenheit (200 Celsius).

Step 4

Meanwhile: In the same skillet, heat a little oil, add minced onion and sliced mushrooms, and sauté for 10 minutes on medium-low heat, stirring occasionally. Add soy sauce, oregano, black pepper and stir well.

Step 5

Transfer the mixture to a food processor and add olives (make sure there are no stones in them). Process until smooth-ish.

Step 6

Unfold/unroll puff pastry sheet and cut it into about 3-3.5 inch (8-9 centimeter) squares. Spread some mustard in the center of each square, then spread some mushroom mixture over. Top with a piece of beef. Grab 2 opposite tips of the pastry and fold them over the beef. Repeat with the other two corners/tips. Make sure to press down the corners so they don’t open during cooking.

Step 7

Transfer the parcel onto a baking tray (see note 6 & lined with baking parchment. Repeat with the rest of them. Brush them with beaten egg.

Step 8

Bake in a preheated oven at 400 Fahrenheit (200 Celsius) for 10-15 minutes or until the pastry is puffed and golden brown.

Step 9

Best served warm with a dipping sauce of your choice.