Blanch the asparagus in boiling water for one minute, then refresh under cold running water (this retains its vibrant green colour and keeps it crisp). Cut in half lengthways.

Mix all the other ingredients except the bread in a bowl, and season to taste. For the final stage, heat a chargrill pan till smoking. Lay bread on the pan and drizzle with a bit of oil. Turn them over when they get browned and nicely stripy from being charred, but not too burnt. Add more oil as you need to. You can do this ahead of time and then crisp them up in a warm oven. To assemble and serve, place the slices on a plate, spoon over some crab mixture and garnish with some rocket leaves.