Preheat the oven to 400°.
Cooked Vegetables: Spread the potatoes on sheet trays lined with parchment paper and drizzle on 3 tablespoons of olive oil and season with salt and pepper.
Spread the shallots out on a separate sheet tray lined with parchment paper and in a small bowl whisk together the remaining 2 tablespoons of olive oil, balsamic vinegar, and sugar.
Next, brush the shallots with the mixture and place all of the trays in the oven.
Cook the potatoes for 20 minutes or until lightly browned and cooked.
Cook the onions for 25 minutes basting with the balsamic mixture every 6 to 7 minutes.
Cream Sauce: Next, in a medium-size bowl whisk together all of the ingredients until combined and keep cool.
To Plate: Spread a layer of the cream sauce on the bottom of a toasted Kaiser bun and then add on some arugula leaves. Next add the beef followed up with some toasted russet and sweet potatoes, some balsamic shallots, sliced radishes, and kale. Finally, top off with the other toasted Kaiser roll.