Food & Cooking Recipes Lunch Recipes Portobello Mushroom Burger with Spicy Avocado Sauce 3.7 (29) 3 Reviews By Martha Stewart Editors Martha Stewart Editors Facebook Instagram Twitter Website An article attributed to "Martha Stewart Editors" indicates when several writers and editors have contributed to an article over the years. These collaborations allow us to provide you with the most accurate, up-to-date, and comprehensive information available.The Martha Stewart team aims to teach and inspire readers daily with tested-until-perfected recipes, creative DIY projects, and elevated home and entertaining ideas. They are experts in their fields who research, create, and test the best ways to help readers design the life they want. The joy is in the doing. Editorial Guidelines Updated on June 12, 2017 Print Rate It Share Share Tweet Pin Email Prep Time: 25 mins Total Time: 50 mins Servings: 4 Even carnivores will give this hearty burger the thumbs up. Ingredients 4 large portobello mushrooms, stems removed 1 tablespoon olive oil Coarse salt and ground pepper 1 ripe avocado, pitted, peeled, roughly chopped 1 tablespoon spicy brown mustard 1 tablespoon horseradish 1 tablespoon fresh lime juice 1 jalapeno chile, finely chopped (ribs and seeds removed, for less heat), if desired 4 soft rolls, split horizontally 1 beefsteak tomato, cored and thinly sliced Directions Preheat oven to 425 degrees. On a large rimmed baking sheet, toss mushrooms with oil and 2/3 cup water; season with salt and pepper. Arrange stemmed side down; cover loosely with foil. Roast until tender, 30 to 45 minutes. Meanwhile, in a medium mixing bowl, mash avocado with a fork. Stir in mustard, horseradish, and lime juice. Fold in jalapeno season with salt and pepper. Toast rolls. Dividing evenly, layer each bottom half with tomato and portobello, and each top half with avocado mixture. Rate it Print