Start by freezing the butter. Measure 150g, wrap it in foil and place in the freezer for about 1 hr.

Place the flour in a bowl. Using the coarse section of the grater, grate the butter into the flour. If it’s clumping, dip the butter into the flour.

Using a spatula, wooden spoon, etc - something that’s not your hands - stir the butter into the flour a bit to distribute it evenly.

In a glass mix the 2 tablespoons of mustard with 2 tablespoons of cold water.

Still using the spatula, stir about half of this liquid into the flour mix. Then do the same adding the other half of the liquid.

Once the water-mustard is mixed in, using your hands - as briefly as possible - bring the dough into one mass. If it’s too dry to do this add half a tablespoon of water.

Place in a bag / cling film and put in the fridge for a minimum of 30 minutes to rest.

Place the pastry on a lightly floured surface and roll out so that it’s over 15cm (6 inches) tall and around 30cm to 45cm wide.

Using a knife, trim the pastry so that it’s into a rectangle.

Mix the 3 tablespoons of mustard into the sausage meat. Also mix the 1 tablespoon of mustard into the egg yolk.

Roll the sausage meat into a cylinder the width of the pastry and place in the middle of the pastry.

Brush the top of the pastry with the egg wash.

Roll the bottom of the pastry over the sausage meat, then keep rolling the pastry and sausage meat upwards to fully encapsulate the sausage in pastry.

Preheat the oven to 200°C (392°F) for a fan oven.

Egg wash the sausage roll and top with seeds, if using them.

Using a sharp knife, cut the sausage roll into 4.

Place on grease proof paper on a baking tray and bake for around 30 minutes until golden and crispy.

Take them out of the oven and either serve straight away or allow to cool.