Method:
1 Heat a char-grill pan over medium heat, brush sausages and onion with oil and grill for 6-8 minutes or until sausage is cooked though and onion caramelized. Remove to a plate. 
2 In the same pan, drizzle bread with a little oil, grill sourdough until toasted.
3 Arrange sourdough on a plate, top with sliced tomato, sausage, onions, basil and season with salt and pepper, serve