Whisk the miso paste with 1-2 tbsp of water to dissolve it. Then, in a medium bowl, combine the broth, nutritional yeast, soy sauce and miso mixture. Whisk well and set aside.
In a medium pot, start by warming up the oil (if using), then add the onion and cook on low-medium heat. Stir often and let them cook until softened and caramelized, about 20 min (or more!).
Then, add the crushed garlic and keep cooking while stirring for about 30-60 seconds.
Add the flour, stir to incorporate within the onions and cook for about 1 minute. Then add the broth mixture and whisk until uniform. Turn up the heat to medium-high and bring to a simmer while whisking often. Keep simmering until the sauce thickens, about 8 minutes, keeping in mind that it will keep thickening after done or cooling down.
You can either serve the gravy as is or blend it to a smooth texture (or partially blended).
Serve over mashed potatoes, vegan meatloaf, vegan meatballs, lentil shepherd's pie or with your favorite comfort food meal. Enjoy!