Vegan stuffed portobello mushroom | Meaty portobello mushrooms stuffed with wild rice and herby caramelized onion and spinach. Topped with toasted panko with herbs and baked until golden brown. This recipe makes the perfect vegan dinner.
Stuffed mushrooms are always a crowdpleaser. Especially when you stuff them with flavourful herby fillings. I stuffed these vegan portobello mushrooms with wild rice, which is slightly chewy in texture and earthy in flavour. I also add caramelized onions flavoured with garlic, thyme, rosemary, sage and a splash of balsamic vinegar.
These flavour pairings are classic and work so well with the wild rice and portobello mushrooms. To top it all off, I top the mushrooms with herby toasted panko breadcrumbs for a satisfying crunch. You could also top the mushrooms with cheese, or vegan cheese, in the last few minutes of baking.
Most of the ingredients used in this portobello mushroom recipe are simple ingredients, and pantry staples. And if you don’t have fresh herbs, you can used dried herbs. You can also replace the wild rice with white or brown rice, or even quinoa, millet or couscous.
This vegan stuffed mushroom recipe is super simple and is perfect for feeding a group. Double the recipe to make 8 mushrooms to feed a larger group. You could also make the filling and stuff small mushrooms, like cremini mushrooms, to create an easy vegan appetizer.
In this portobello mushroom recipe I use 4 tablespoons of vegan butter, for the breadcrumbs, the rice and the filling itself. If you want to skip the butter, use olive oil in the rice and the filling, but just dry toast the breadcrumbs instead.
How to make vegan stuffed portobello mushrooms
Stuffed mushrooms are so simple yet versatile. I went with earthy, herby flavours by using wild rice, caramelized onion with balsamic vinegar, spinach and various herbs. Start by cooking the rice and letting it cool. Then caramelize onions and add the chopped mushroom stems, spinach and garlic. Add a bunch of herbs like thyme, sage and rosemary. Then finish it off with a splash of sweet balsamic vinegar. Mix in the rice and stuff the cleaned and prepared portobello mushroom caps. Top with toasted herby panko breadcrumbs and bake for 20 minutes.
How to prepare portobello mushrooms
First, wipe the mushrooms down with a paper or cloth towel to remove any dirt. Rinsing mushrooms in water can cause them to become waterlogged. Flip the mushrooms over, cap side down, and trim the edges so that they’re smooth and straight. Then, twist the stem with your fingers to remove it. Use a small spoon to scoop out the dark gills. They are edible, but unsightly, so I remove them to create more room for filling. Set the stems aside to use them in the filling.
How to caramelize onions
Turning pungent raw onion into soft almost gooey caramelized strands of onion is such a fun and rewarding process. Caramelizing onions is a slow process and it can take anywhere from 15-45 minutes. Start by melting 2 tablespoons of butter in a stainless steel pan. Add sliced raw yellow onion to the melted butter and cook, stirring frequently until they start to become soft and translucent, about 2-3 minutes. Then let the onions cook undisturbed for 1-2 minutes. Add a splash of water, and scrape the onions up from the bottom of the pan. This releases all the flavourful darkened bits. Continue this process, adding more liquid when it evaporates, and letting the onions cook undisturbed.
More about the ingredients in this recipe. The exact measurements are below.
Line a baking sheet with parchment paper. Clean the portobello mushrooms and remove the stems. Use a small spoon to scoop out the dark gills. Discard the gills and chop up the stems to use in the filling.
Heat a pan on medium heat and add a tablespoon of butter. Once it’s melted and bubbling, add the panko breadcrumbs. Toast for 1-2 minutes, stirring frequently. Add 1/4 teaspoon of each herb, and salt and pepper. Cook for 1 more minute. Remove from heat and set aside.
Add 2 tablespoons of butter to a pan and heat on medium low heat. Once melted, add the onion. Cook until soft and semi translucent, then cook for 1-2 minutes without touching them.
Add a splash of water (1-2 tablespoons) and stir, scraping the bottom of the pan. The onions will become more brown each time you do this. Repeat the process, cooking untouched, then adding water and stirring, until they’re soft and dark. About 15 minutes.
Add the chopped mushrooms stems and cook for 2-3 minutes, stirring frequently so the onions don’t burn. Add a splash of water if needed. Add salt and pepper to taste.
Now preheat the oven to 350°F.
Add the spinach, herbs, and garlic. Cook for 30-60 seconds. Add the balsamic vinegar and stir. Remove from the heat. Taste the mixture and add more salt and pepper if needed.
Add the rice to the onion mixture and stir to combine.
Fill the mushrooms with the rice and onion mixture, pressing it into the mushroom so that the top is flat.
Add the breadcrumbs to the top of the mushrooms, in a neat flat pile.
Bake for 20 minutes. The mushrooms will crinkle up on the sides and release some liquid. Remove from the oven and serve. Sprinkle with pepper and fresh parsley.
Tips for making vegan stuffed mushrooms
What to serve with vegan stuffed portobello mushrooms
Stuffed portobello mushrooms create the perfect main dish. Some sides you can enjoy with the stuffed mushrooms include a simple garden salad or an apple kale salad. For a starchy side, roast some potatoes, cauliflower or squash.
For an easy side, try hummus and vegetables or a chickpea salad.
You can’t go wrong with a side of garlic bread, or garlic naan.
If you’re feeling like a sauce with the mushrooms, try a vegan gravy, or a tahini sauce.
Store the mushrooms in an air tight container, or wrapped in plastic wrap, in the fridge for up to 2-3 days. To freeze stuffed portobello mushrooms, freeze before coooking. When you want to cook one, let it thaw in the fridge and then bake.
To reheat stuffed portobello mushrooms, cook at 300°F for 8-10 minutes. If top starts to burn, cover with aluminum foil.
You’ll need to buy portobello mushrooms but you can stuff the mushrooms with many pantry staples. Choose a starch, like rice or quinoa, some vegetables and your favourite fresh or dried herbs.
A garden salad, kale and apple salad, or chickpea salad go well with stuffed mushrooms. Starchy sides like roasted potato or cauliflower also go really well.
It usually takes 20-25 minutes to bake stuffed portobello mushrooms. The sides should be crinkly, and the mushrooms should release some liquid.
Vegan Stuffed Portobello Mushrooms
- 1 baking sheet
- 1 cutting board
- 1 knife
- 1 spoon
- 1 stainless steel pan
- 1 wooden spatula
- ½ cup uncooked wild rice plus 1 cup water
- 4 tablespoons vegan butter or oil, divided
- 4 portobello mushrooms cleaned, gills discarded, stems set aside
- ¾ cup panko breadcrumbs
- 1 ¼ teaspoon fresh thyme divided
- 1 ¾ teaspoons fresh sage divided
- ¾ teaspoon fresh rosemary divided
- ½ yellow onion thinly sliced
- 150 grams thawed frozen spinach
- 2 garlic cloves minced
- 1 teaspoon balsamic vinegar
- salt and pepper to taste
- Line a baking sheet with parchment paper and set the prepared mushrooms on it, the side you scooped out facing up.
- Add the wild rice, 1 tablespoon of butter and the water to a pot, cover with a lid and bring to a boil on high heat. Lower the heat to medium low and simmer for 20 minutes. Remove from the heat and let sit for 5-10 minutes before fluffing with a fork.
- Heat a pan on medium-low heat and melt 1 tablespoon of butter. Add the panko breadcrumbs and cook for 1-2 minutes, stirring frequently. Add 1/4 teaspoon of thyme, sage and rosemary, salt and pepper, and cook for 1 more minute. Remove from the heat and set aside.
- In the same pan, melt 2 tablespoons of butter. Add the onions and cook for 3-4 minutes, stirring occasionally. Then, cook for 1-2 minutes undisturbed. Add a splash of water, and scrape the onions from the bottom of the pan. Repeat this process, replacing the water when it evaporates, until the onions are dark and soft, about 15 minutes.
- Roughly chop the mushroom stems and add them to the onions. Cook for 2-3 minutes, stirring frequently. Add a splash of water if the onions start to burn.
- Now preheat the oven to 350°F.
- Add the spinach, the remainder of the herbs, garlic, and salt and pepper to the onions. Cook for 30-60 seconds. Add the balsamic vinegar and stir. Remove from the heat and set aside.
- Add the rice to the onion mixture. Taste and add more salt and pepper if needed.
- Fill the mushroom caps with the rice filling, pressing the mixture in so that the top is flat. Top with the breadcrumbs, in a neat flat pile.
- Bake for 20 minutes, or until the sides are crinkly and the mushrooms release some liquid. Remove from oven and serve with fresh parsley or thyme.
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