1. Preheat the oven to 200°C, gas mark 6. Heat the oil in a frying pan and fry the sausages for 3 minutes to brown, add the orange and onion marmalades and cook for 1 minute. Transfer to a small roasting tin and bake for a further 15 minutes.
2. Meanwhile, mix together the mayonnaise and mustard and spread over the bread.
3. Brush the gem hearts with a little oil and griddle for 1-2 minutes each side and place on top of 2 slices of bread. Top with the sausages and spoon over the juices, top with remaining 2 slices of bread and serve.