Mushroom Wellington, by Dianne Wenz - Jazzy Vegetarian - Vegan and Delicious!

Ingredients

• 2 tablespoons neutral-flavored vegetable oil, divided
• 1 yellow onion, diced
• 2 garlic cloves, minced
• 6 large portobello mushrooms, stems trimmed, cut into 1-inch thick slices (approx.)
• ¼ cup dry red wine
• 2 tablespoons balsamic vinegar
• 1 teaspoon Dijon mustard
• 1 tablespoon chopped fresh rosemary leaves
• 1 tablespoon chopped fresh thyme
• ½ teaspoon salt
• ¼ teaspoon black pepper
• 5 cups loosely packed baby spinach (about 5 ounces)
• 1 sheet vegan puff pastry