Light your fire and let it burn down for 1 hour until you have nice coals. (Or use hardwood charcoal.)
Heat a medium cast-iron frying pan over the coals, add the chillies and let them char a little. Take the pan off the heat and rest for 5 minutes, then add the oil and put the pan back on the heat to infuse for 1 hour while the fire is warming.
Meanwhile, put your lobsters to sleep in a bucket of ice with a lid on it. This will take an hour or so.
Slice each lobster head to tail, brush with chill oil and place, flesh-side down, on the grill. Cook for 5 minutes, then flip them over and brush with some more chili oil. Sprinkle with the garlic and cook for another 5 minutes or until the flesh is cooked though. Remove from the heat and let rest for 5 minutes.
Pull the lobster meat out of the shell and place in a bowl. Add 1/4 cup mayonnaise, the lemon zest and herbs and gently toss to coat. The lobster should be lightly coated, but not weighed down by the mayo. Add the remaining tablespoon of mayonnaise, if needed.
Taste the lobster salad. Some brands of mayo have more tang than others; if the salad needs more brightness, add a squeeze of lemon juice. Season to taste with salt and pepper.
Spread some extra mayo over the inside of the hotdog buns and grill for 1–2 minutes on each side or until toasted to your liking. Place a lettuce leaf in each bun, and fill with a generous mound of lobster salad.
