01 - Whisk together olive oil, soy sauce, lemon juice, minced garlic, dried oregano, black pepper, and salt in a bowl until fully combined.
02 - Add beef cubes to the marinade, toss thoroughly to coat, cover, and refrigerate for at least 1 hour, up to 4 hours for maximum flavor absorption.
03 - If using wooden skewers, soak in water for 30 minutes prior to threading to prevent scorching during grilling.
04 - Thread marinated beef cubes, bell pepper pieces, and onion chunks alternately onto skewers, distributing ingredients evenly.
05 - Brush assembled kebabs lightly with olive oil and season with additional salt and pepper to taste.
06 - Preheat grill or grill pan to medium-high heat, approximately 375-400°F.
07 - Place kebabs on preheated grill and cook for 10-15 minutes, rotating every 3-4 minutes, until beef reaches desired doneness and vegetables show slight charring with tender texture.
08 - Remove from heat and let kebabs rest for 5 minutes to allow juices to redistribute throughout the meat.