Wash hands with soap and water.
Scrub the onion and garlic with a clean vegetable brush under running water. Cut the onion into 1-inch pieces and mince the garlic.
In a shallow sealable container, whisk together olive oil, lemon juice, garlic, vinegar, mint, oregano, salt and pepper.
Cut the pork tenderloin into 2-inch chunks. Do not rinse raw meat.
Add the pork and onions to the marinade. Wash cutting board, counter and utensils after touching raw pork. Wash hands with soap and water after handling raw pork.
Refrigerate the pork, onion, and marinade mixture for at least 30 minutes or up to 12 hours.
When ready to cook, remove the pork and onions from the marinade, and thread onto skewers, alternating the pork with the onions. Leave a small space in between to allow for even cooking. If using bamboo skewers, soak them in water first to prevent burning. Do not reuse marinades used on raw foods.
Wash hands with soap and water after handling raw pork.
Heat a grill or grill pan over medium-high heat. Grill the kebabs until the internal temperature of the pork reaches 145 °F on a food thermometer with a three-minute “rest time” after removal from the grill.
Scrub lemon with a clean vegetable brush under running water. Garnish with lemon wedges.
Serve with grilled red onion, eggplant, zucchini and/or pita bread. Scrub onion, eggplant and zucchini with a clean vegetable brush under running water before preparing.