In a small bowl mix mayo, mustard and sriracha and set aside.
Slice French bread lengthwise. Place on a baking sheet cut side up. Layer ham slices on the bottom side and top with Swiss. Add more Swiss to the top and bake for several minutes until the cheese is melted and ham is warm. Turn the broiler on the last minute of baking just to brown the cheese a little bit.
Remove from oven and top with shredded lettuce, tomato slices, pickles, red onion, peperoncinis and the mayo sauce. Place both sides of the sandwich together and cut into desired lengths. Serve promptly while the sandwich is warm and gooey.
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