Vegan Shepherds Pie

Name: Vegan Shepherd's Pie
Ingredients: 4 tbsp. vegetable oil, divided; 1 lb. shiitake mushrooms, torn into large pieces; 1 large onion, diced; 2 celery stalks, finely diced; 2 parsnips, diced into 3/4-inch pieces; 1 small butternut squash, peeled and chopped into 1-inch pieces; 6 cloves garlic, minced; 1 tbsp. double concentrated tomato paste; 1 tbsp. white miso paste; 0.5 red wine; 1 c. dry green lentils, rinsed; 2 tbsp. flour; 4 c. vegetable stock