Cook the broad beans in a saucepan of boiling water for 4 minutes until tender. Drain the beans, then refresh under cold running water and drain again. Slip the beans out of their grey skins, discarding the skins.
Place the beans in a food processor with the garlic and pulse until roughly chopped. Add the lemon rind and juice and then, with the motor running, trickle in the oil through the feed tube. Process until smooth and season to taste with salt and pepper.
Spread a little goats' cheese on each slice of toasted ciabatta, top with the hummus and serve garnished with watercress leaves.