Preheat the oven to 180C/350F/ gas mark 4. Spread the bread on a flat tray, brush with oil and sprinkle with salt. Bake for 12 minutes, until golden, remove and allow to cool.
On a coarse cheese grater, grate the radish into a fine sieve and add half a teaspoon of salt. Mix, then leave for half an hour. Squeeze the radish to remove as much liquid as possible and transfer to a bowl. Add the remaining ingredients, stir and season to taste.
When ready to serve, pile the bread with plenty of the crab topping and garnish with radish cress.
