Use a sharp knife to slice into the chicken breasts and open out flat like a book. Brush both sides with olive oil and a good pinch of salt and pepper.
2.
Place a griddle pan over a high heat and griddle the chicken for 5 minutes on each side, or until charred and cooked through. Remove from the pan and leave to rest for a few minutes. Then slice the chicken into strips and season with salt and pepper.
3.
Trim the lettuce and halve, destone and cut the avocado into slices, using only half of it. Slice the tomato.
4.
Spread a thick layer of Heinz [Seriously] Good Mayonnaise on both slices.
5.
Place all the ingredients on to the sourdough, drizzle olive oil on top.
6.
In a panini grill pan or cast-iron skillet, cook until the bread appears crispy.
