As your potatoes are steaming, let's prepare the gravy.
In a small pot, combine the mushrooms with the water and finely chopped Rosemary. Bring it to a boil, then let the contents simmer.
Moving onto the rest of the gravy, in a skillet roast the oil and the garlic together until it becomes fragrant. Then add the flour, nutritional yeast, and coconut aminos and stir to form a smooth paste. Gradually whisk in the broth. Season with salt and pepper. Bring to a boil and add the contents of the mushroom pot to the skillet of gravy. Reduce heat, and simmer, stirring constantly, for 8 to 10 minutes, or until thickened.
While the gravy is thickening, use a potato masher to mash the steamed potatoes. Mix in the Earth Balance, the vegetable broth and mustard. Salt and pepper to taste.
Serve the potatoes and gravy hot n steamy together!