Sift the flour and salt into a bowl.

Coarsely grate the cold butter into the flour, regularly dipping the butter into the flour to stop it sticking to the grater.

Mix the grated butter through the flour with a round bladed knife: try not to break up the butter.

Add the lemon juice to the chilled water.

Gradually add all the liquid to the flour and butter mixture, stirring it in with the knife until the dough starts to come together.

Bring the dough together into a ball using your fingertips then place it on the lightly floured work surface.

Shape the dough into a chunky block then, with a short side facing you, roll into a rectangle approximately 45x15 cm.

It doesn't matter if your rectangle looks very rough: it will gradually neaten as you fold it during the next steps.

Pick up the bottom third of the dough and fold it over the middle third.

Now pick up the top third and bring it down over both.

Seal the open sides by pressing firmly with the rolling pin.

Wrap the dough in foil or cling film then put in the fridge for 15 minutes.

Unwrap the dough and, with the folded sides to left and right, roll it into a rectangle again. Fold as before and seal the open sides again. Rewrap the dough and chill for 15 minutes.

Repeat this process THREE more times then leave in the fridge until ready to make the sausage rolls.

Heat the olive oil in a frying pan over low-medium heat then add the chopped onion, fennel seeds, and season with salt and pepper. Cook, stirring often, until soft and golden (approx12-15 min).

If using the optional apple and/or garlic, add to the pan for the last 5 minutes.

Put the sausagemeat in a bowl, along with the breadcrumbs if your sausagemeat does not already contain them or similar filler such as rusk (see Recipe Notes).

Add the contents of the frying pan to the bowl along with the optional fresh herbs if using.

Mix everything together well: using your hands is best.

Recommended: take a teaspoon of the mixture, form it into a patty and fry. Taste and adjust the seasoning of the sausagemeat if necessary.

Preheat the oven to 200C / 180C Fan / Gas 6.

Grease or line a large baking tray

In a small bowl, beat the egg with the splash of milk and set aside.

Take the pastry from the fridge, unwrap it and place on a lightly floured work surface.

Roll into a square approximately 4-5 mm thick.

Cut the square into two rectangles.

Put one of the rectangles aside for now and place the other so that a long side is facing you.

Take half of the sausagemeat filling and place it in a long horizontal line roughly ⅓ up the dough.

Brush all the edges of the dough with some of the beaten egg and milk.

Roll up the pastry to enclose the sausagemeat and press firmly on the join to seal it.

With the sealed edge underneath, make slashes all along the length of the dough. Using a sawing motion so as to not squash the dough, cut it into 8 equal pieces (or less if you want larger sausage rolls).

Place on the prepared baking tray.

Repeat with the other pastry rectangle and remaining sausagemeat.

Brush the sausage rolls with the remaining egg and milk mixture.

If adding the optional sesame and/or nigella seed garnish, sprinkle them over and brush with another layer of glaze.

Put in the preheated oven and bake until risen and golden brown (25-35 min).

When done, transfer the sausage rolls to a wire rack to cool a little.

Serve warm or leave until completely cold and store in an airtight container.

Use within 3-4 days or freeze for 1 month.