It’s unfortunate but true: stuffed portobello mushrooms used to get a bad rap. Being a vegetarian in the early aughts, I was often left with very few meatless hands to choose from when it came to eating out. Having selected my only option from the menu, a waiter would inevitably appear with a large portobello cap centered on the plate. No accompaniments or garnishes — just a giant baked mushroom. I’d be lucky if I could swallow a single rubbery, bland bite. Needless to say, when it came to portobellos, I was scarred. So what’s a recipe developer to do but create stuffed portobello mushrooms that are actually palatable, and dare I say, delicious.
The last few years have seen a mushroom renaissance. From King Oyster to Hen of the Woods, mushrooms have become a part of the culinary zeitgeist and are a joy to eat. In many kitchens (my own included), mushrooms are lauded as a functional superfood and treated like a powerhouse ingredient.
I’ll eat mushrooms any and every way I can. While I’m partial to shiitake or maitake, I’ve recently fallen in love with the earthiness of portobello mushrooms. They’re great on their own, adding a meaty heft to omelets and pasta, but I’ve converted to stuffed portobello mushrooms, enjoying all the deliciousness I can. Nothing inspires like incorporating new ingredients into a staple dish, and many iterations of stuffed portbello mushrooms later, I’ve found the combination I’ll make now until forever. The best part? You only need five ingredients to cook up a little mushroom magic.
How to Cook Stuffed Portobello Mushrooms
I can’t take credit for this trick, but one thing I discovered while making this recipe a few times was that mushrooms, when roasted, release a lot of water. I’m used to sautéing mushrooms in a pan, so I never gave this issue much thought. But when baked on a sheet tray, the mushrooms sit in their liquid and turn soggy.
After doing a little research, I found this method that lets the mushrooms breathe while baking on an oven-safe cooling rack. This allows the extra liquid to drain off, helping the mushrooms cook through. Game changer.
Don’t have an oven-safe cooling rack? I’ve also done this by cooking the mushrooms first stem-side up and then flipping them so they cook all the way around. Worst-case scenario, sop up the liquid with a kitchen towel before stuffing the mushrooms. Trust me: Trying any of these simple tricks will make all the difference.
The Filling: How to Caramelize Onions
Caramelized onions are truly one of the gems of the recipe world — scratch that, the food world in general. The magic that happens when onions cook down, getting golden and sweet, is a total treasure. But I won’t lie, I’ve burned my fair share of pans in the process and been left with a few sticky, unpleasant results. But after countless batches, I’ve found a method that gets caramelized onions, in all their sweet and jammy glory, just right.
- Start with chopped and diced onions. In lieu of long strands, chopped and diced onions give your stuffing a tastier texture.
- Use a large pan. Larger than you think you need! The onions need room to cook over direct heat. If you pile them in a small pan, they’ll steam and get soggy. No thanks.
- The more oil, the better. Starting with a few extra glugs helps keep everything smooth and glossy in the early stages of cooking. If your pan feels dry while cooking the onions, add more oil as needed.
- Cook low and slow. Avoid high heat at all costs! Cooking your onions at a higher temperature will dry the pan and burn your onions. I keep the heat on low to medium-low and adjust as needed. It might take a minute to find the right balance between constantly stirring and letting the onions sit against the heat, but it’s well worth the effort.
- Deglaze with vinegar. I love balsamic or apple cider vinegar to deglaze the pan once your onions are almost done cooking. A little splash at the end will pick up all the golden bits sitting on the pan. Plus, the vinegar will add a nice bite of acidity to the onions that complements the sweetness perfectly.
Caramelized onions take a little babysitting and a bit of time. But when cooked this way, the final result yields so much flavor.
Tips for Next-Level Stuffed Portobello Mushrooms
So you have your tray of stuffed mushrooms. Now what?
I like serving my stuffed portobello mushrooms with a really bright and acidic salad. Crisp greens with a zingy lemon dressing make for a perfect pairing. If you think your plate could use some carbs, serve a pot of rice alongside. Bread is always a delicious option, too.
Once you’ve wrapped up your meal, don’t worry about leftovers. Personally, I find that stuffed portobello mushrooms don’t keep very well, but I have found a tasty solution for next-day deliciousness. If you have a few mushroom caps left, place them on a cutting board, chop, and dice them into small cubes. This includes the filling, too. Store in the fridge in an airtight container.
The next day, sauté the leftovers in a pan and toss them into an omelet or frittata. Or, make a big pot of pasta while you sauté the mushrooms in butter. Add the cooked pasta to the mushrooms with a little of the pasta water plus Parmesan for added decadence. With leftover stuffed portobello mushrooms, anything is possible.