Preheat the oven to 200°C / 180°C fan / gas mark 6 and line a baking tray with baking paper.
Add the flour and salt to a large bowl and mix together.
Rub in the chilled dairy-free baking block with your fingertips until the mixture looks like fine breadcrumbs.
Add 2 tablespoons of cold water and mix gently until the pastry starts to come together. Add the extra tablespoon only if needed.
Bring the pastry together into a dough, wrap if needed, and chill for 10–15 minutes while you prepare the filling.
In a bowl, mix the sausage meat with the dried sage, onion powder, garlic powder, and black pepper.
Lightly flour the work surface and roll the pastry into a rectangle.
Cut the pastry in half lengthways to make two long strips.
Divide the sausage mixture into two long sausage shapes and place one down the centre of each strip.
Fold the pastry over the filling and press the edges together to seal.
Turn each long roll so the sealed edge is underneath, then cut each one into 4 pieces.
Place the sausage rolls on the prepared tray and brush the tops lightly with dairy-free milk.
Bake for 22–25 minutes until golden and cooked through.
Leave to cool slightly before serving.