Pre-heat the oven to 160degC/Gas 3/Fan 140. Place the olive oil, ginger, cumin, coriander, turmeric, juice and zest of the lemon, the stalks of the coriander and a good pinch of salt into a blender and blitz to from a smooth paste. Put the shoulder of lamb onto the two large pieces of foil and make lots of incisions with a knife. Next rub the paste all over. Add a couple of tablespoons of water then seal the foil leaving a little pocket of air above the lamb. Place onto a baking sheet and cook for 4 hours.
After 4 hours open the foil and baste the lamb. Put the garlic bulb into the oven. Cook for a further hour when the lamb should be meltingly tender and the garlic soft. Meanwhile place all the ingredients for the salsa into a mixing bowl, season well and mix thoroughly to combine. Turn off the oven but leave the lamb to rest inside.
To make the aioli:
Gently heat the olive oil. Squeeze out the really soft insides of the garlic cloves into a blender. Add the egg yolks and some salt and pepper. With the motor running add the olive oil to make a smooth thick sauce.
Place into a heavy-based saucepan so you can heat through before serving (this could also be done in with a small whisk and a bowl).
Heat the bread in the oven by wrapping in a clean damp tea towel. Shred the lamb using two forks. Give each person a piece of bread smear over the garlic sauce, top with some lamb, a good spoonful of the salsa and finish with some rocket and a couple of slices of the cucumber. Wrap and eat immediately.