1-Pot French Onion Soup (Vegan!)

Name: 1-Pot French Onion Soup (Vegan!)
Prep time: 5 min
Cook time: 1 h
Total time: 1 h 5 min
Cuisine: European, Mediterranean, French
Ingredients: 2 Tbsp oil or vegan butter ((or sub twice the amount in water, plus more as needed to prevent sticking)); 2 medium yellow onions, peeled + sliced into slightly larger than 1/4-inch rounds; 1 healthy pinch each salt and black pepper, plus more to taste; 2 cloves garlic, minced; 1 cup thinly sliced shiitake mushrooms ((adds depth of flavor and a bit of texture // okay to omit)); 1 Tbsp arrowroot starch or cornstarch ((optional // or all purpose flour if not gluten-free)); 2 bay leaves; 1 ½ tsp fresh thyme leaves, lightly chopped ((or sub 3/4 tsp dried thyme)); 4 cups vegetable broth; 1 Tbsp coconut aminos ((or sub half the amount with tamari as it’s saltier)); 2 tsp miso paste; Croutons ((gluten-free as needed // see notes for instructions))