Preheat the oven to 425 degrees F. Combine the paprika, red pepper flakes, cumin and 2 teaspoons salt in a shallow dish. Rub the pork all over with the olive oil, then roll in the spice mixture to coat. Transfer to a roasting pan and roast until a thermometer inserted into the thickest part of the meat registers 145 degrees F, 15 to 20 minutes. Transfer to a cutting board and let rest, 5 minutes.
Meanwhile, bring a large pot of salted water to a boil. Add the quinoa and cook until tender, about 10 minutes. Drain and fluff with a fork. Toss with the corn, scallions, and salt and pepper to taste.
Slice the pork and drizzle with olive oil. Serve with the quinoa and salsa verde, if desired.
Quinoa is a nutty-tasting high-protein grain. If you can't find it, use couscous.