In a bowl, whisk olive oil, soy sauce, Worcestershire sauce, lemon juice, garlic, paprika, oregano, salt, and pepper.
Add steak cubes to the marinade, cover, and refrigerate for at least 1–2 hours (or overnight for best flavor).
Preheat grill to medium-high heat.
Thread steak, peppers, onion, and zucchini onto skewers alternately.
Brush with extra marinade before grilling.
Grill kabobs for 10–12 minutes, turning occasionally, until steak reaches desired doneness.
Remove from grill and let rest 5 minutes before serving.