Here’s a simple but exceptionally tasty way to cook portobello aka flat mushrooms (also called field mushrooms or “BBQ mushrooms”). The appeal lies in how the herb butter soaks deeply into the mushrooms, and in the sliced green onions that lend a distinct flavour and attractive emerald colour to the dark, roasted mushrooms.
This recipe is ideal for serving mushrooms as the centrepiece of a meatless meal, or as a starter for a multi-course dinner!
Roasted large mushrooms
Everybody loves mushrooms, and this low-effort recipe for serving chunky portobellos makes a great vegetable side to accompany any number of dishes, like sizzling steaks, Sticky Grilled Chicken and Garlic Prawns. With their beefy texture and topped with this flavoursome melted butter, they’re also substantial and interesting enough to star as a main course for vegetarians or omnivores alike.
Herbs bring fragrance and colour, while the green onions add another layer of interest to the flavour and steps away from the usual garlic-and-butter routine.
How good does this look!!! (That’s a rhetorical question, by the way… 😂)
What you need for these roasted Flat Mushrooms
Here’s all you need to make these roasted Flat Mushrooms:
Large mushrooms – Any large mushrooms that are around 10cm /4″ or larger in diameter are ideal for this recipe. You just need mushrooms large enough so you can slather the cups with the green onion and herb butter. And remember, they’ll shrink a fair bit when cooked!
You’ll find them sold labelled with various names here in Australia. Flat mushrooms, field mushrooms, BBQ mushrooms, portobello mushrooms. Just go by size!
Butter – Softened, so we can mix in the herbs.
Thyme and parsley – The herbs of choice here. Thyme, because thyme loves mushrooms, and parsley for freshness.
Green onions / shallots – Called scallions in the US, this adds a vibrant splash of green as well as fresh allium goodness. The onions stand in for delicious-but-a-little-predictable garlic, for something a little different. (Of course, feel free to also add garlic – it certainly won’t hurt!)
Mushrooms – Cleaning, preparing, storing
How to clean mushrooms – Clean mushrooms by removing dirt using a cloth or paper towel. If you’re going all out or need to get into the cracks and crevices, use a pastry brush! Though these days, grocery store mushrooms are sold pretty clean.
Contrary to common wisdom, you can in fact also wash mushrooms to clean them too. They will absorb a tiny amount of water but it’s negligible. So as long as it’s quick wash, they will not go watery or slimy.
Should I remove mushroom gills? Mushroom gills are totally edible and I never remove them, unless I’m making specific types of stuffed mushrooms where I want to make room for more filling. Some people say they don’t like the flavour of the gills (eg dusty flavour), I’ve never experienced that.
However, if you don’t like the gills, just remove them using a spoon. Cradle mushroom in one hand, gently work the tip of a spoon under the gills and scoop around – it will come off with little effort.
The stem – If your mushroom has a very long stem, trim it so it’s the height of the edge of the mushroom, or snap it off (with fresh mushrooms, the stem will break off neatly).
How to store mushrooms – Always store mushrooms in a breathable bag, such as a brown paper bag or wrapped in a tea towel. If you use plastic bags or containers, the mushrooms will sweat, the surface will go slimy and the shelf life of the mushrooms will be considerably shorter.
How to make Roasted Flat Mushrooms
It could not be quicker or easier – 3 easy steps!
Mix softened butter with green onions and herbs;
Slather onto mushrooms; and
Roast 25 minutes until cooked through. That’s it!
Satisfying and yet so simple. We need more recipes like this in the world!
So, what do you think? How will you serve these – as a main or as a side? – Nagi x
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Roasted Flat Mushrooms with Green Onion, Thyme & Butter
Ingredients
- 8 large mushrooms (flat, portobello, “BBQ”), around 10 – 12cm / 4 – 4.5″ wide, stem tips trimmed (Note 1)
Herb & Green Onion Butter:
- 100g / 7 tbsp unsalted butter , softened
- 1 cup green onion (US:scallions), thinly sliced
- 1/3 cup parsley , finely chopped
- 1 tbsp fresh thyme leaves (sub 1 tsp dried)
- 1/2 tsp salt
- 1/4 tsp black pepper
Garnishes (optional):
- 3 tbsp chopped scallions
- 1 dozen thyme stalks
Instructions
- Clean mushrooms: See Note 1.
- Preheat oven to 200°C / 390°F (180°C fan).
- Mix butter: Mix the Herb & Green Onion Butter ingredients together in a medium bowl.
- Smear mushrooms: Place mushrooms gills side up on a large tray. Smear the butter mix over the mushroom surfaces. Cover with foil (preserves green colour of herbs).
- Bake: Bake 25 minutes, until mushrooms are tender.
- Serve! Arrange on a platter, including all butter and juices on tray. Scatter with thyme stalks and extra scallions over the mushrooms (for a fresh touch), and serve.
Recipe Notes:
Nutrition Information:
Life of Dozer
Come on Dozer! You can do it – climb, climb! (And climb he did – bit of slipping and sliding going on, but he got to the top of the “mountain”!)
Hi Nagi, I am going to make this mushroom salad for dinner tomorrow. Can’t wait. They look great and I love mushrooms. Hope you tested negative to COVIDS. A lot of people we know are testing positive now., at least those who did not wear masks. Anyway. I hope you are ok. Good luck. Give my love to Dozer! He is wonderful.
My family and I loved the portabella mushroom salad…with seasoned butter, chives, parsley and thyme it was a delicious appetizer!
Served as an entrée last night. Extremely easy to prepare and very tasty! Will make again!
Hi Nagi, always love your recipes and these were so delicious! Definitely a keeper. Thankyou for this recipe.
I’m so glad you enjoyed it, that’s great!! N x
Love your other stuffed and roasted mushroom recipes so looking forward to trying this one 😀
I hope you love this one too Helen! N x
Love your recipes. Hope you and your helper are vaccinated. Will try two of todays suggestions .Can’t get the Japanese ingredients here and am too lazy now to travel for them . FINGERS CROSSEDRE TESTS!
Love Dozer.
THANKS.E.
Sorry, can’t vote for any one of the salads, which do you leave out? They all look sensational and will be making all three. Fingers crossed your C19 tests come back clear.
I have a vegetarian friend so this one will be perfect when we can host guests again! My fingers are crossed for you and your helper that your tests come back clear .
Mushrooms are meat for vegetarians, I’m sure it will be a hit Ailsa! N x
D’lishus. Thank you. The pear and blue cheese is one of our old favourites. I will definitely be making it tonight.
That’s awesome Marilyn!! N x
Please remember to advise people to scoop out the gill of the mushroom as it’s bitter and it’ll impact the taste of any marinade used.
Hi Lickety, you actually don’t need to do this – I talk about this in the post 🙂 N x
Of the three salads, I definitely will not be trying this one. To me, mushrooms taste like dirt. I avoid them at all cost. Although I don’t like blue cheese either, some of the substitution suggestions sound like a plan. As for the seaweed, I’ll pass on that too. Have tried many of your recipes with great success, and I love the Dozer photos and comments. Hope you stay safe and the quarantine was just a precaution.
Maybe these salads aren’t for you then Joanie!! I have stacks more though, I’m sure I’ll have lots that you’d enjoy! N x
Can’t wait to try this – it sounds and looks delicious as a side for beef especially.
Yes exactly Patricia – love to know if you try them! N x
Stay safe, Nagi and Dozer. We’re praying for you!
Thanks so much Theresa! N x
The mushroom salad looks delicious!! Just added Portobello’s to my list!!!!
Excellent Cathy!!! Enjoy! N x
The mushroom salad looks delicious!! I will be trying this one this week, thank you!!
If the mushrooms are actually picked in a paddock then you missed a vital step: rib-side down, then tap-tap-tap. That knocks out any stray insects. It’s the traditional way, though theoretically a bit of extra cooked protein shouldn’t hurt.
PS Stripping off the top skin from a mushroom removes any cow-pat taint.
I generally don’t pick mind from the wild thankfully 😂 N x
Oh my stars, this salad looks amazing. Salad is one of our go to things for dinner. This will be fixed once I get to the store to get fresh ingredients. As always stay safe and hope your test comes back negative. Scratches for Dozer since he can’t go for a walk!
A lovely sounding and simple recipe that my vegan son will love – just need to swap out the butter for a vegan spread. Thank you.
That will work perfectly fine Mary! I hope they are a hit! N x
I absolutely love Portobello mushrooms and your very ‘green method of preparation. For me such would be the ‘hero’ of any meal, so perhaps on their own as a lunch dish or two as a side to a simply marinated and grilled paillard de veau or juicy fillet of chicken. Do hope your test comes back negative . . . you do mot need that extra . . .
Sounds perfect Eha!! N x
We have fingers and everything else crossed for you and yours Nagi. Stay well.
Thanks so much Lorraine! N x