Portobello Mushroom Burgers (Roasted or Grilled)
You don’t have to give up beef to love these portobello burgers. A 3-ingredient marinade creates incredible flavor, and they’re simple to cook in the oven or on the grill. The recipe is also easy to scale to any number of diners.
Ingredients
- 4 portobello mushrooms caps (look for large ones, ideally at least as wide as a hamburger bun)
- 2 tablespoons (30ml) low-sodium soy sauce or gluten-free tamari
- 2 tablespoons (30ml) freshly squeezed lemon juice
- 2 tablespoons (28ml) olive or avocado oil
- 4 hamburger buns, toasted
- Optional toppings: arugula, butter lettuce, baby spinach, or greens of choice; sliced or mashed avocado; cheese (like Boursin*, blue cheese, fontina, gruyere, Swiss, provolone, or mozzarella), sriracha mayo (see notes); pesto; sliced tomato; thinly sliced red onion or pickled onions; thinly sliced cucumber; and/or other favorite burger toppings
Instructions
- Prep the portobellos: Use a paper towel to gently rub the portobello mushrooms to help remove any dirt and trim the stem if it is prominent. With a soup spoon, scrape out the gills and discard. (Technically, the gills are fine to eat if you prefer to skip this step.) Arrange the portobellos in a glass baking dish with the stem-side facing up. (Alternatively, you could use a large, zip-top bag.)
- Marinate the portobellos: In a small bowl, stir together the soy sauce, lemon juice, and olive oil. Use a spoon to pour the mixture over the mushrooms, and then use your hands to rub the sauce on the outside of the mushrooms too. (If using a zip-top bag, seal, and gently move around to coat them in the marinade.) Let the portobellos marinate for 15 minutes or so.
- To roast the portobellos: Preheat the oven to 400ºF. Drain off the excess marinade and place the mushrooms, stem-side up, on a lightly greased or sprayed baking sheet. (For easy cleanup, line with foil or parchment.) Roast the mushrooms for 15 minutes, and then flip them over (before flipping, I pour off any accumulated liquid – mushrooms emit a lot) and bake for an additional 10 minutes or until the mushrooms are tender.
- If using cheese: Drain off additional liquid as needed. If desired, top with cheese and roast another 1 minute until the cheese melts. Or you can put the cheese on the toasted bun and place back in the toaster or oven for a minute to melt.
- To grill the portobellos: Follow the same instructions but cook on a grill that has been preheated to medium. Start with rounded side down, grilling (with lid down) for 5-7 minutes, depending on thickness, until lightly browned. Flip and cook the other side for about 3-5 minutes more. (It’s tough to overcook the mushrooms; they won’t be dry as they are naturally very high in moisture. You just don’t want to burn them with too much direct heat. More than focusing on time, I look for nice grill marks and deep golden color.)
- If using cheese, you can flip the mushrooms back over and place the cheese on top (in the concave part, not on the rounded side where it will likely slide off). Close the lid for a minute or so to allow the cheese to melt. Or add the cheese to the toasted bun towards the end of toasting to get it a little melty.
- Serving: With either method, serve warm on a toasted bun with your favorite toppings.
- Storage: Leftover mushrooms can be stored in an airtight container in the fridge for 3-4 days.
Notes
*Serving ideas: One of my favorite ways to top the burger is to spread a thick layer of softened Boursin cheese over the toasted bun. To make it extra creamy, briefly put the bun back in the warm toaster or on the grill. From there, I add thinly sliced cucumber for crunch and some arugula, butter lettuce, or other greens if I have some on hand. Serve with a few potato chips on the side – and tuck a few chips in the burger for added crunch!
Buying portobellos: I’ve been finding large portobellos that are sold in 18-ounce packages of five. In this case, for adequate marinade, I make 1½ times the recipe – 3 tablespoons of each. When in doubt, make the larger amount to ensure even coating. Any excess marinade is drained off anyway. That said, you could reserve it and drizzle over cooked rice or other grains and vegetable sides.
To make a simple but delicious sriracha mayo, mix 1 tablespoon of sriracha with ¼ cup of mayonnaise. If you prefer less spice, you may wish to start with 1-2 teaspoons of sriracha—and you can always add more mayo or sriracha to taste. The flavored mayo tastes great on regular burgers, too, and if you make a bigger batch, leftovers will keep in an airtight container in the refrigerator for quite a few weeks.
Smoked Paprika Aioli is delicious on portobello burgers too.
One more thing: While the mushrooms cook, you could grill onions slices that have been brushed or sprayed with olive oil for a minute or two on each side. You can also quickly toast the bun on the grill too.
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