Soak the kombu in 5 cups of boiling hot water and set aside.

Meanwhile, cut the stems off the mushrooms. Using a knife, thinly slice the tops off the mushrooms, then with your hands, shred the base into thin strips.

Heat the avocado oil in a large non-stick skillet over medium heat. Once the oil is hot, place the mushrooms in an even layer and cook, without stirring, until most of the liquid cooks out, 8 to 10 minutes. Season the mushrooms with 1 teaspoon of the Old Bay seasoning, the garlic powder, and 1 tablespoon of the vegan butter. Continue to cook, while stirring, until the outer edges start to crisp, and the mushrooms turn a deep brown color, another 8 to 10 minutes. Set aside.

Place the remaining 8 tablespoons of butter in a large pot or Dutch oven over medium heat. Once the butter is melted, sauté the onion, carrots, and celery until translucent, 2 to 3 minutes. Add the garlic and sauté another 1 to 2 minutes, until fragrant. Sprinkle in the flour and give it a good mix until incorporated. Add the bouillon cubes and remaining Old Bay seasoning, and continue to cook, while stirring, 1 to 2 more minutes.

Slowly whisk in the kombu water (including the kombu pieces) and bring to a simmer while whisking to ensure there are no clumps. Once at a simmer, add the vegan dish sauce and potatoes and give it another good mix. Reduce the heat to medium low, cover, and simmer until the potatoes are slightly tender, 10 to 12 minutes.

Remove the lid and pour in the non-dairy milk. Remove the kombu pieces and continue to simmer, uncovered, until the potatoes are fork tender and the soup thickens, 7 to 10 minutes. Add the reserved mushrooms, then taste and adjust seasonings if necessary.

Serve immediately with fresh minced parsley and vegan bac’n bits and enjoy!