• Preheat oven to 375ºF.
• Cover a large baking sheet with a piece of parchment paper or foil (optional, but helps with cleanup).
• Unwrap the crescent rolls and carefully separate them into their 8 triangles. Arrange the unrolled triangles on the baking sheet
• Spoon the oil into a large skillet. Use a paper towel to spread the oil over the surface in a thin, even layer.
• Heat the pan over medium heat, until water droplets flicked onto the surface sizzle.
• Fold or scrunch each mortadella slice into a bundled, narrow rectangle and place on the hot pan. Leave enough room between the slices so you can pick them up.
• Let the mortadella bundles fry on the first side for 2 or 3 minutes. The underside should take on golden edges, but not burn.
• Use tongs to carefully flip each bundle to the other side, and fry for another 2 to 3 minutes.
• Take one of the provolone half slices and tear it in half. Lay the two quarters on one of the mortadella bundles. Repeat with the remaining cheese halves and mortadella bundles.
• Let the cheese melt. This will take several minutes, but can be speeded up by placing a lid (or even a large sheet pan) over the skillet, to trap heat and steam.
• Transfer one mortadella bundle to the wide edge of one of the crescent roll triangles. Spoon a small amount of mustard on the dough next to the mortadella. Roll up the crescent biscuit starting at that wide end. Reposition the roll with the pointed end of the dough visible on top.
• Repeat with the remaining rolls. If necessary, rearrange the rolls on the sheet so there's plenty of room for expansion as they bake.
• Bake the rolls per package direction, 10 to 13 minutes.

If topping the rolls with butter and seasoning:

• While the crescent rolls bake, melt the butter in a small pot on the stove or container in the microwave.
• When the biscuits have a golden hue, brush each roll generously with butter and sprinkle seasoning over the top, pressing down lightly to help the seeds stick to the butter.
• Return to the oven for another minute or two.