Mushroom Wellington | Heinen's Grocery Store

Ingredients

• 1 large red onion, sliced
• 1 Tbsp. butter
• 2 tsp. balsamic vinegar
• 1/4 tsp. salt
• 1/8 tsp. black pepper
• 2 cups carrot, diced
• 2 cups celery, diced
• 4 cloves of garlic, minced
• 2 Tbsp. olive oil
• 24 oz. baby Bella mushrooms, sliced
• 1/4 cup red wine
• 2 tsp. thyme
• 2 tsp. Worcestershire
• 1 tsp. salt
• 1/4 tsp. black pepper
• 1 package frozen puff pastry, thawed according to package instructions
• 1 egg yolk