In a small bowl whisk the mayonnaise, Sriracha and ponzu together until completely combined.
In a medium mixing bowl stir the lobster meat, mayonnaise mixture, celery and onion until completely incorporated.
Cover and refrigerate the lobster salad until ready to serve.
Make a slice on the top of each roll, making sure to leave the bun in once piece. Heat a large sauté pan over medium heat, add butter and allow it to melt. Toast the rolls on both sides until golden brown, about 1 minute each side.
Add a piece of the lettuce to each roll. Scoop the lobster mixture into the roll until it is filled and garnish with green onion. Serve immediately.