Preheat a heavy-based frying pan over medium-high heat with a little poultry fat or oil, and pan-fry the sausages for 5 to 6 minutes, turning frequently on all sides until golden brown.
METHOD FOR THE LEEKS
Place the oil into a small fry pan or pot and heat over medium heat. Once the oil is approximately 150ºC, fry the leeks using a slotted spoon, lowering the leeks into the oil. Fry them for about 1 to 2 minutes or so, just until they turn golden.
Transfer to a plate lined with a paper towel to drain.
METHOD FOR SERVING
Lightly toast the split brioche roll, then fill with the hot chicken sausage, top with the sauces and crispy leeks.