Place shrimp in a large bowl and using a paper towel pat shrimp until dry, add mustard. Stir until shrimp is completely coated with mustard. Add 1/2 a bag of seafood fry mix and toss until coated

Add oil to a cast iron. Once the oil temperature reaches 360 degrees, gently place shrimp in the oil. Fry for about 3-5 minutes, flipping shrimp half way through. Once golden brown and cooked through, remove shrimp from oil onto a paper towel lined plate

Slice french bread in half, spread mayo on bread, add shrimp, place tomatoes on one side and top with shredded lettuce