In a large bowl, whisk together the oil, soy sauce, worcestershire, vinegar, mustard, honey, garlic, pepper, paprika, and italian seasoning.
Add the steak and peppers. Toss until well combined.
Add the onions and toss gently so the onions do not completely separate. (This makes threading them on the skewers easier.) Cover and marinate in the refrigerator for a minimum of one hour or overnight.
Preheat the oven to 450 degrees. Skewer the steak and veggies, alternating as you like. I recommend 3-4 pieces of steak per skewer.
Repeat with remaining steak and veggies to make about 6 kabobs. Place on a rimmed baking sheet lined with foil. Do not pour excess marinade on top.
Bake for 10-15 minutes, depending on what temperature you prefer your steak. Broil for 5-7 minutes or until charred, watching closely so they do not burn. (Medium rare is about 130 degrees and medium is about 140 degrees.)