Pre-heat the grill of your oven on the hottest setting.
Combine the ingredients for the jalapeño mayo and set aside.
Do the same with the salsa ingredients.
To assemble the sandwich, place the chicken on two slices of the sourdough then top with the mozzarella. Place the sandwiches on a baking tray and place in the oven.
Allow the cheese to melt and become golden brown then remove from the oven.
Spread the mayo on the remaining slice of bread then top the sandwich with the avo slices and a generous spoonful of salsa. Top with the fresh coriander and close the sandwich with the mayo-slathered bread.