Beef Kebab Marinade

Name: Beef Kebab Marinade
Ingredients: 1/3 c. balsamic vinegar; 1/3 c. Worcestershire sauce; 1/3 c. olive oil; 2 garlic cloves, grated; 1/2 tsp. ground black pepper; 1/4 tsp. red pepper flakes (optional); 2 tbsp. honey, divided; 2 tbsp. Dijon mustard, divided; 1 1/2 lb. sirloin or New York strip, cut into 1-inch cubes; 8 oz. baby portobello mushrooms, large stems removed; 1 red onion, cut into 1-inch pieces; 1 green bell pepper, cut into 1-inch pieces; 1 yellow bell pepper, cut into 1-inch pieces; 1 red bell pepper, cut into 1-inch pieces; Chopped fresh parsley, for garnish