Preheat the oven to 400°F. Sprinkle the pork with 1/4 tsp. salt and pepper. Heat 1 Tbs. olive oil in an oven-safe pan over medium-high heat. Brown the pork on all sides, about 5 minutes. Transfer to the oven and cook for 15 minutes or until the internal temperature reaches 145°F. Let rest for 5 minutes then slice into 1/2-inch thick medallions.
In a large bowl toss the lettuce with 1 Tbs. olive oil and 1/4 tsp. salt. Divide among serving plates. Top with the pork, cucumber, walnuts, and cranberries. Serve with lemon wedges.