1. Trim the silver skin from the tenderloins. Stir the 2 Tbsp (30 mL) of olive oil with the garlic, oregano, lemon zest, salt and pepper and rub this over the tenderloins. Cover and chill for 1 hour.
2. For the salad, toss together the peppers, cucumber, tomato, onion, oil, vinegar, and parsley and then season to taste. Sprinkle the top of the salad with the crumbled feta just before serving. The salad can be prepared up to 4 hours ahead of time.
3. Preheat the grill to medium-high, and remove the pork from the marinade. Grill the pork, with the grill lid closed, for about 10-12 minutes per side until they read 145°F (63 °C) on a thermometer and remove to rest on a cutting board for 5 minutes. Slice each tenderloin across the grain into 6 round slices and serve with the Shopska salad. Use some of the juices from the salad to dress the tenderloin.