Slice the avocado in half and remove the stone. Prick all over with a fork, or cut criss-cross patterns with a knife. This allows the sauce to penetrate the flesh.
Pour the sauce over each half, then top with lime juice and salt and pepper.
In the cavity where the stone has been, put a quarter of the cheese on each avocado half.
Place under the hot grill for 2 minutes.
Top with remaining cheese and grill for another 2 minutes until completely melted and avocado warmed through.
Eat hot with a wedge of lime and chipotle sauce on the side!