Place the first twelve ingredients in a large ( 34x 28 cm) baking tray. Mix very well, then spread the sausages out. Pour the water into the tray around the sausages ( don’t get them wet).
Roast for 35 to 40 minutes, turning the vegetables- but not the sausages- a couple of times. The sausages should be cooked through and the vegetables golden brown.
While this is cooking place a large non stick frying pan on a high heat. Once very hot place the citrus halves cut side down in the pan and char for 3-4 minutes until the cut sides are nicely charred ( press down on the citrus to make sure they char evenly).
For the salsa chop the cucumber into 1 cm cubes. Mix with the lime juice, oil and salt. Stir in the herbs just before serving.
Transfer the contents of the baking tray to a platter . Squeeze over the charred citrus then stir in the beans, if using. Top with some of the cucumber salsa and serve the rest on the side.