In a bowl add the drained tuna fish, enough mayonnaise to make spreadable and mix thoroughly.
Cook some bacon, let cool and crumble. Set aside - this is optional.
Chop the jalapeño rings and stalk of celery into fine dice. Add to tuna fish mixture along with cheese and optional bacon at this point if you like, I switch it up and sometimes omit. Season to taste with Bob's Big Boy seasoning salt or your favorite. Add the crackled black pepper and mix.
Spread the Dijon Mustard over the sourdough bread on one side and layer with the tuna fish mixture. Top with other piece of sourdough bread and butter both outsides. Sprinkle a little Bob's Seasoning salt on each side if you like, too.
Brown the tuna fish sandwich on each side, being careful not to burn. Remove from pan, let cool slightly an enjoy.