These are my favorite shish-kabobs:
Marinade:
1/2 c. olive oil
1/4 c. vinegar, wine or sherry (I prefer red wine)
1/4 c. chopped onion
1 tsp. salt
2 tsp. worchestershire sauce
garlic to taste
Blend ingredients together, then marinate overnight 2 lbs. sirloin tips (1 inch
pieces), mushrooms (I prefer baby portobellas), green pepper cut into chunks,
and onions cut into chunks.

After marinating, skewer meat and vegetables, and broil for 20 minutes (or
grill outdoors), basting often. May add tomatoes for last 5 minutes if desired.

I usually make extra marinade, and use it to cook rice in as a side dish!
This may also be used for a vegetarian kabob. Simply leave out the meat and
marinate vegetable chunks such as zucchini, green pepper, etc.