Preheat oven to 400°F.
In a large bowl, toss kale with 4 tablespoons oil, lemon juice, currants, and pecorino; season with salt and pepper and set aside.
On a rimmed baking sheet, drizzle sweet potatoes with 2 tablespoons oil; season with salt and pepper and toss to coat.
Roast, flipping once, until potatoes are tender, about 25 minutes.
In a pot, bring quinoa, ¾ cup water, and a pinch of salt to a boil.
Reduce heat, cover, and simmer until tender, 15 minutes.
Let stand 5 minutes. Fluff quinoa with a fork; transfer to a plate to cool.
Heat remaining 1 tablespoon oil in a 10-inch ovenproof skillet (preferably cast iron) over medium-high.
Generously season pork with salt and pepper; sear, turning occasionally, until golden, about 8 minutes.
Transfer to oven and roast until a thermometer reads 145°F, 8 to 10 minutes.
Transfer pork to a cutting board; let stand 10 minutes before slicing.
Stir potatoes and quinoa into kale salad and serve with pork.
