Place the mushroom caps in a large glass bowl and drizzle 1 tablespoon of soy sauce over them; use a spatula to gently toss them in the mixture, until evenly coated. Set aside and let marinate while you prepare the filling, tossing occasionally.

Bring a medium pan to medium-high heat; Add the pine nuts and walnuts to the pan and toast for 5 minutes, stirring frequently to prevent burning.

Add the onion and celery to a food processor and process until they are very finely chopped, almost at a chunky paste. Remove from the food processor and set aside. Then, add the toasted nuts, garlic, nutritional yeast, rosemary, thyme, paprika, sage, and black pepper to the food processor. Pulse until the nuts are very finely chopped, almost resembling coarse breadcrumbs. Reserve 3 tablespoons of this mixture to top the mushrooms; place the rest in a separate bowl apart from the onions/celery.

Heat the vegan butter in a nonstick pan over medium high heat. Once warm, add the onion and celery mixture. Sauté for 5 to 7 minutes, until the onion is translucent and slightly golden. Deglaze the pan with the remaining 1 tablespoon of soy sauce. Then, add the ground nut & spice mixture to the pan; cook for 1 minute, to allow the nuts and spices to toast. Add the red wine to the pan and stir well into the mixture; it should begin to stick together and form a thicker “paste.” Sauté for an additional 5 minutes, stirring occasionally. Season with salt and additional pepper to taste, if necessary.

Place each mushroom cap into the baking dish with the hollow side (where the stem used to be) facing up. Fill each mushroom with approximately 1 tablespoon of the cooked filling, using your fingers to press it in firmly (though some will remain on top). Sprinkle the reserved nut & spice “breadcrumbs” over each mushroom.

Bake in the top rack of the oven on 200 degrees for 25 minutes, until the mushrooms have fully cooked and the topping is golden brown.

Serve on top of rocket salad and drizzle with a dressing of your choice.