Vegan Shepherd's Pie with Polenta and Lentils

Ingredients

• 4 cups vegetable stock
• 2 cups unsweetened, unflavored plant-based milk
• 2 cups dry polenta
• 2 tablespoons nutritional yeast
• 2 teaspoons sea salt
• 1 teaspoon baking soda
• ½ teaspoon freshly ground black pepper
• 1 lb. mushrooms, thinly sliced (about 7 cups)
• 1 medium onion, diced (2 cups)
• 1 red bell pepper, diced (1 cup)
• 12 cloves garlic, minced
• 2 bay leaves
• 1 tablespoon dried oregano
• 1 teaspoon dried thyme
• 1½ cups vegetable stock
• ¼ cup oat flour
• 2 (15-ounce) cans brown lentils, rinsed and drained (3 cups)
• 1 (16-ounce) bag of frozen mixed vegetables
• 1 tablespoon white wine vinegar
• 1 tablespoon fresh parsley (plus more for garnish)
• Sea salt
• freshly ground black pepper
• Hot sauce (optional)