Marinated Beef Kebabs

Ingredients

• 1/2 c. vegetable oil
• 2 Tbsp. cider vinegar
• 1 tsp. celery salt
• 1 tsp. onion salt
• 3/4 tsp. garlic salt
• 1/2 tsp. salt
• 3/4 tsp. crushed oregano
• 1/2 tsp. pepper
• 1 boneless beef shoulder, cut into 1-inch cubes
• 6 medium mushroom caps
• 2 small zucchini, cut in 1/2-inch pieces