You are here: Home » Recipes » Portobello Mushrooms Portobello Mushrooms Recipe by dshuell Yield 6 servings PrintEmail Ingredients 6 portobello mushrooms1 cup canola oil1/4 cup balsamic vinegar1/4 cup soy sauce2 tablespoons minced shallots3 tablespoons minced garlic Instructions Do not wash mushrooms. Remove stems. Mix remaining ingredients together and pour over mushrooms. Let marinate at least for 1 hour. Preheat oven to 300F. Place mushrooms in a roasting pan. Place in oven and roast 1 hour.