Savory Portobello & Mixed Mushroom Puff Pastry

1. Prepare Portobello Mushrooms

Start by cleaning the portobello mushrooms with a damp paper towel, removing the stems, and trimming the rims. Brush them with 3 tablespoons of olive oil, sprinkle with kosher salt and black pepper, and sear in a nonstick skillet over medium-high heat until they are browned on both sides. This should take about 10 minutes. Set them aside to cool.

2. Prepare Mushroom Filling

Finely chop the mixed mushrooms. Heat 1/4 cup of olive oil in a large skillet over medium heat and add half of the chopped mushrooms, half of the shallots, half of the garlic, and half of the fresh rosemary. Season with kosher salt and black pepper and cook until the mushrooms release their moisture and it evaporates, about 10 minutes. Repeat with the remaining mushrooms and aromatics. Combine both batches in a large bowl. Stir in the port or aged balsamic vinegar, soy sauce, fresh thyme leaves, and toasted walnuts. Set the bowl over an ice bath to cool, stirring occasionally, for about 20 minutes.

3. Caramelize Onions

While the mushroom mixture cools, caramelize the onions. Melt 3 tablespoons of unsalted butter in a skillet over medium heat. Add the yellow onion rounds, light or dark brown sugar, kosher salt, and black pepper. Cook, stirring occasionally, until the onions are soft and golden brown, about 20 minutes. Pour in the apple cider and cook until it reduces and the onions are nicely caramelized. If desired, add a tablespoon of aged balsamic vinegar for extra depth of flavor. Cool the onions slightly.

4. Assemble Puff Pastry

On a lightly floured surface, roll out the puff pastry into a rectangle and transfer it to a parchment-lined sheet pan. Spread the cooled mushroom mixture evenly over the pastry, leaving a border around the edges. Layer the caramelized onions on top, followed by the seared portobello mushrooms. Carefully fold the edges of the pastry over the filling, sealing the edges to enclose it completely. Brush the pastry with the beaten large egg to give it a golden, glossy finish. Decorate the top with any extra pastry cutouts if desired.

5. Bake Puff Pastry

Bake the puff pastry in a preheated 375°F (190°C) oven for 45 to 50 minutes, or until the pastry is golden brown and crisp.

6. Prepare Port Reduction Sauce

While the puff pastry bakes, prepare an optional port reduction sauce. Heat 2 tablespoons of olive oil in a medium saucepan over medium heat. Add the minced shallot, minced garlic, and whole black peppercorns, and cook until softened. Pour in the port and vegetable stock, add the fresh thyme sprigs, and bring to a boil. Reduce the heat and let it simmer until the liquid is reduced by half. Strain the sauce, return it to the pan, and whisk in 3 tablespoons of unsalted butter until smooth. Season to taste.

7. Serve

Once the puff pastry is baked to perfection, let it cool slightly before slicing. Serve the slices with a drizzle of the port reduction sauce if desired. Enjoy!