01 - Whisk together olive oil, soy sauce, lemon juice, minced garlic, dried oregano, black pepper, and salt in a mixing bowl until well combined.
02 - Add beef cubes to the marinade, toss thoroughly to coat, cover the bowl, and refrigerate for at least 1 hour (up to 4 hours for optimal flavor absorption).
03 - If using wooden skewers, soak them in water for at least 30 minutes before grilling to prevent scorching.
04 - Thread marinated beef, bell pepper pieces, and onion chunks alternately onto skewers, ensuring even distribution of ingredients.
05 - Lightly brush assembled kebabs with olive oil and season generously with salt and pepper.
06 - Preheat grill or grill pan to medium-high heat, approximately 400°F.
07 - Grill kebabs for 10 to 15 minutes, turning every 3 to 4 minutes, until beef reaches desired doneness and vegetables display slight charring and tenderness.
08 - Remove kebabs from heat and let rest for 5 minutes to allow juices to redistribute before serving.