In a bowl add the drained tuna fish, enough mayonnaise to make spreadable and mix thoroughly. Chop the jalapeño rings and stalk of celery into fine dice. Add to tuna fish mixture. Season to taste with salt. Add the crackled black pepper and mix. Spread the Mahram Mustard over the Toast bread on one side and layer with the tuna fish mixture. Top with other piece of Toast bread and butter both outsides. Brown the tuna fish sandwich on each side, being careful not to burn. Remove from pan, let cool slightly an enjoy.