01 - Whisk olive oil, lemon juice, oregano, smoked paprika, minced garlic, salt, and black pepper in a large bowl.
02 - Add beef cubes to the marinade and toss to coat evenly. Cover and refrigerate for at least 15 minutes, up to 2 hours for enhanced flavor.
03 - Heat the grill or grill pan to medium-high. Soak wooden skewers in water for 20 minutes to prevent burning if using them.
04 - Thread beef, bell pepper pieces, and red onion wedges alternately onto skewers.
05 - Cook the skewers for 10 to 12 minutes, turning occasionally until beef reaches desired doneness and vegetables are lightly charred.
06 - Transfer to a platter, garnish with chopped parsley, and serve with lemon wedges.