Vegan gravy

Name: Vegan gravy
Prep time: 10 min
Cook time: 40 min
Total time: 40 min
Yield: 10 portions
Ingredients: 20 g extra virgin olive oil; 80 g brown onion; 130 g carrot; 1 celery stalk; 1 garlic clove; 25 g dried porcini mushrooms; 1 sprig fresh thyme; 1 dried bay leaf; 1 tbsp arrowroot flour; 1 tsp shiro (white) miso paste; 1 tbsp tomato paste; 1 tsp stock paste; 750 g water; ½ tsp salt