White Wine Vinegar: I used white wine vinegar, but you can also use apple cider vinegar if you prefer.

Sugar: I used white sugar, but feel free to use light brown sugar, dark brown sugar or coconut sugar. Alternatively, if you are diabetic or insulin-resistant, I highly recommend using granulated monkfruit sweetener (a 1:1 sugar substitute that is zero glycemic index and will not raise your blood sugar).

Tomato Sauce: You can use a storebought or homemade tomato sauce. Alternatively, you may also use tomato ketchup if you prefer.

Olive Oil: I like using extra virgin olive oil for its flavor, but you may also use another vegetable oil (such as sunflower oil, corn oil, avocado oil). You can also use melted vegan butter. Alternatively if you are not lactose-intolerant, feel free to use melted butter or ghee instead.

Onions: I used yellow onions, but you can also use white onions or red onions (or a mix of all three!). Sliced onions are most commonly used in French onion soup, but you may also use diced onions.

Gluten-Free All-Purpose Flour: I used gluten-free all-purpose flour to keep this recipe gluten-free. You can also use tapioca starch or arrowroot starch instead. However, if you are not Celiac or gluten-intolerant, feel free to use normal flour instead.

Beef Broth: Traditionally, beef broth is used in making French onion soup, but you may also use beef stock or chicken stock if you prefer. If you wish to keep this recipe vegetarian, feel free to use vegetable stock instead. If you are Celiac or gluten-intolerant, make sure to use gluten-free beef broth.

Tamari: I used tamari (a gluten-free version of soy sauce) to keep this recipe gluten-free. You may also use coconut aminos if you prefer.

Cornstarch: Cornstarch is used as a thickener to thicken the soup, but you may also use tapioca starch or arrowroot starch if you prefer.

Thyme: Adding dried thyme adds a beautiful flavor to the French onion soup. Alternatively you may use fresh thyme, but only add the fresh herbs towards the end of the cooking process.

Garlic Powder: I love adding garlic powder because it adds plenty of flavor. Alternatively, you can use granulated garlic instead.

Onion Powder: Adding onion powder also contributes to the onion flavor in this soup. Alternatively, you can use granulated onion instead.

Black Pepper: A sprinkle of ground black pepper adds a slight kick of heat, but feel free to leave it out if you aren’t a fan of pepper.

Croutons: I used gluten-free croutons to keep this recipe gluten-free, but if you are not Celiac or gluten-intolerant, you may use normal croutons instead.

Mozzarella Cheese: I used dairy-free mozzarella cheese to keep this recipe dairy-free, but if you are not lactose-intolerant, you may use normal mozzarella cheese instead.

Make Ahead: If making the soup beforehand, do not add the croutons or mozzarella until you are ready to eat or serve the onion soup. Place the soup in an airtight container and store in the refrigerator for up to 4 days. Reheat the soup in a pot or the microwave before topping with croutons and cheese.