Vegan Mushroom Pie With Melted Leeks & Herbs

Ingredients

• 4 tablespoon extra-virgin olive oil, divided
• 2 large or 3 medium leeks, tough outer layers removed, halved lengthwise, washed very well and white and pale green parts sliced thinly
• 1 pound mixed mushrooms, sliced (a mixture of shiitake, cremini, oyster, maitake, and trumpet would be excellent)
• Kosher salt and freshly ground black pepper, to taste
• 1 pinch red pepper flakes
• 2 tablespoon vegan butter (substitute more olive oil if you don’t like or have this)
• 2 cloves garlic, finely chopped
• 5 to 6 sprigs thyme, leaves only
• 5 5 to 6 sage leaves, thinly sliced into ribbons
• 1 tablespoon white miso
• 2 tablespoon all-purpose flour
• 1/4 cup dry white wine, cider vinegar, or apple cider (hard or not)
• 1 3/4 cup vegetable stock or plain unsweetened oat milk (for a richer texture), at room temperature
• 2 tablespoon nutritional yeast (optional)
• 1 sheet vegan puff pastry (like Pepperidge Farm), thawed
• Aquafaba or melted vegan butter, for brushing