For the pastry
1. Put the flour,spices,salt and baking powder in a large mixing bowl and toss to combine with your fingers. Add the butter cubes,coat these in the flour then add the water and milk,and mix. Carefully mix everything to a dough,but leave the butter in lumps as you go.
2. Generously flour the work surface and dough,and try to roll it out as best you can to a strip about 40 centimetres by 20 centimetres. The butter will be lumpy,it'll look a mess,but don't worry. Fold it in by thirds,repeat the rolling and folding once more,using lots of extra flour to stop it sticking,then chill the dough for 30 minutes. Do this twice more and the dough is ready to use.
Note:Pastry freezes perfectly for up to three months if wrapped well.
For the sausage rolls
1. Put the lamb in a bowl with all the remaining ingredients (except the puff pastry,beaten egg and seeds) and mix very well by hand. Chill the mixture for a few hours,or overnight if you can,before using.
2. Roll the pastry dough to half centimetre thickness. Squeeze the filling mixture into a sausage shape that is about four centimetres in diameter and the length of your rolled-out dough. Wrap a single layer of dough around the"sausage". Where the edge of the dough overlaps,seal with a little water and chill to firm.
3. Slice into sausage rolls to a length that suits you and place on a tray lined with non-stick paper. Brush with beaten egg,slash the tops at an angle,sprinkle with onion seeds and bake at 200C/180C fan for about 40 minutes until puffed and golden.
Serve with Dan Lepard'sthree-herb labna andquick mango chutney.