This Iron Man-inspired hero is literal: iron-rich beef tenderloin is coated in a panko breadcrumb suit of armor and topped with iron-rich kale. And just as Iron Man is nothing without his paramour, Pepper Potts, this hero is nothing without the roasted bell pepper relish.
For the beef: Turn the oven down to 325 degrees F. Toast the panko breadcrumbs in a small dry skillet, stirring occasionally, until golden brown, about 5 minutes. Mix together the salt and black pepper, and then sprinkle all over the beef. Heat the oil in a medium skillet over medium-high heat and then add the beef and cook to brown on all sides, about 5 minutes. Remove and let cool enough to handle. Brush the beef with the Dijon, and then pat with the panko breadcrumbs. Transfer to a rack set over a baking sheet or roasting pan and roast until a thermometer reads 125 to 130 degrees F, about 35 minutes. Transfer to a cutting board to rest. Slice the tenderloin 1/4-inch thick.
For the kale: Meanwhile, whisk together the olive oil, lemon juice and mustard in a medium bowl. Add the kale and season with salt and black pepper.
To assemble, spoon 2 to 3 tablespoons of the pepper relish on the bottom of each roll. Divide the meat among the sandwiches and top with the kale and remaining bread slices.