01 - Whisk together olive oil, soy sauce, lemon juice, minced garlic, oregano, black pepper, and salt in a mixing bowl until thoroughly combined.
02 - Add beef cubes to the marinade, toss to coat completely, cover the bowl, and refrigerate for at least 1 hour or up to 4 hours for optimal flavor penetration.
03 - If using wooden skewers, submerge them in water for at least 30 minutes prior to grilling to prevent burning during cooking.
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 freshly ground black pepper.
06 - Heat grill or grill pan to medium-high temperature, approximately 400-450°F, ensuring proper preheating for optimal searing.
07 - Place kebabs on the preheated grill and cook for 10-15 minutes, rotating every 3-4 minutes, until beef reaches desired doneness and vegetables show slight charring.
08 - Remove kebabs from heat and let rest for 5 minutes to allow juices to redistribute throughout the meat before serving.