In a large bowl mix together the flour and salt.

Add the cubed cold butter and work it into the flour. You can either use a pastry cutter or work with your hands. If you're using your hands, you have to work fast so as not to melt the butter. Rub in all the butter in the flour until you have a coarse mixture with small pebbles of butter. This process can also be done in a food processor.

Slowly start adding a tablespoon at a time of cold water, while forming a smooth dough. Your dough might require less or more water.

In a skillet fry the onion together with the garlic for a few minutes until fragrant. Let cool completely.

In a bowl, combine all the ingredients. Set aside in the fridge until ready to use.

Preheat the oven to 200°C or 390°F. Line a baking tray with parchment paper. Set aside.

Divide the dough into two pieces; work with one piece at a time. On a floured surface, open the dough to a large rectangle about 5mm thickness. Cut lengthwise down the middle.

Divide the filling into 4. Place the filling down the middle of the cut rectangle shaped dough. Brush the edges with the egg wash. Fold and roll the dough to form a long sausage roll, pinch and close the seam tightly. Place the large roll with the seam facing down, and cut the sausage rolls about 5/6 cm each.

Place the sausage rolls on the lined baking tray, brush with the egg wash and on top sprinkle a mix of sesame and nigella seeds.

Bake for about 20 minutes, until they have a nice golden brown colour and the filling is cooked. If making larger sausage rolls, they will take longer to cook. Cool slightly before serving.