This spinach, tomato, and mushroom burger is loaded with garlicky greens, marinated tomatoes, and a grilled portobello mushroom stuffed between toasted buns. A veggie burger to satisfy everyone.
No ordinary vegan burger, this spinach, tomato, and mushroom burger is piled high with garlicky spinach and tomatoes doused with a unique soy, chile, and ginger marinade. Pleasing to vegetarians and carnivores alike.–Angie Zoobkoff
Spinach, Tomato and Mushroom Burger FAQs
What is the best tomato for a burger?
You’re going to want to choose a large, meaty, flavorful tomato for any sandwich or burger. We’re sort of a bunch of tomato snobs around here, and most of the time the choices at the grocery store are a bit lackluster, so we’re willing to do some extra work in search of the perfect specimen. If you’re looking for the best tomato, explore the farmer’s markets in your area, check with your local CSA, or grow them in your own backyard. We like Brandywine, Morgage Lifters (really!), Beefsteaks, and Rutgers. Choose ripe tomatoes and use them within a couple of days so they’re at their best.
What can I substitute for spinach?
You can substitute any sort of greens to suit your tastes. We’d recommend kale (which would need to cook a bit longer), chard or beet greens, or arugula.
How can I tell if mushrooms are fresh?
If stored properly, mushrooms of any type should remain fresh for about two weeks. For tips on how to store them for maximum freshness, check out this article. When they’re past their prime, there are tell-tale signs.
1. Sight: are they wrinkly with darker spots than you remember? Toss them.
2. Touch: are they dry and firm, or soft and a bit slimy? Dry and firm is good. Mushy and slimy mushrooms are no bueno. Into the trash.
3. Smell: do they smell subtly earthy and well… mushroomy? That’s good. Do they smell like something you don’t want even close to your refrigerator let alone in your mouth? This is an easy one. Chuck them and start over. You may need to wipe out your veggie bin as well.
Spinach, Tomato and Mushroom Burger
For the marinated tomatoes
- 3 tablespoons unseasoned rice vinegar
- 1/3 cup plus 1 tablespoon light soy sauce
- 3 tablespoons light brown sugar
- 1 scallion thinly sliced
- 1/2 red chile pepper such as Fresno or Thai, thinly sliced and, if desired, seeded
- Thumb-size piece ginger root peeled and sliced (optional)
- 2 (about 14 oz) beefsteak tomatoes thickly sliced
For the mushroom burgers
- Pinch each fresh oregano rosemary, and thyme, finely chopped
- 3 1/2 tablespoons (1 3/4 oz) butter room temperature, or 3 tablespoons olive oil (45 ml), plus more for cooking
- 4 large portobello mushrooms
- 1 or 2 garlic cloves sliced
- 1 chile pepper sliced and seeded (if desired)
- 7 ounces spinach
- 1 tablespoon water
- 4 store bought or homemade burger buns toasted, if desired
- Sea salt and freshly ground black pepper
Make the marinated tomatoes
- In a shallow bowl, combine the rice vinegar, soy sauce, sugar, scallion, red chile, and ginger, and stir together to dissolve the sugar.
- Add the tomatoes, turn to coat, and marinate for at least 30 minutes, or as long as overnight, turning occasionally. Transfer to a plate and pat the tomatoes dry.
Make the mushroom burgers
- In a small bowl, mix the herbs with the butter or oil.
- Remove the stems and gills from the mushrooms. Place the mushrooms, rounded caps down, on the work surface. Spread the butter over the gill side of the mushrooms.
- If you’re roasting the mushrooms, preheat the oven to 350°F (180ºC). Line a rimmed baking sheet with foil. Place the mushrooms, butter side up, on the foil and roast until the mushrooms are tender and begin to release their liquid, 10 to 15 minutes. If you’re grilling the mushrooms, preheat the grill to medium-high. Cook the mushrooms, butter side up, on a plancha or directly on the grill over direct heat until tender, 5 to 10 minutes.
- Meanwhile, in a large skillet over low heat, warm a little butter or oil. Toss in the garlic and chile and cook, stirring occasionally, until the garlic turns golden, 1 to 2 minutes.
- Add the spinach to the skillet, carefully dribble in the water, and place a lid or baking sheet on the skillet. Cook the spinach, stirring a couple times, until it wilts, 1 to 3 minutes.
- Season the spinach with salt and pepper. Immediately transfer to a plate, spread it evenly, and let it cool slightly. Pat the spinach completely dry using a kitchen towel or paper towels.
- To assemble the burgers, place a mushroom on each of the bottom buns. Top with the wilted spinach, a couple slices patted-dry tomatoes, and the top of the bun. Devour.
If you make this recipe, snap a photo and hashtag it #LeitesCulinaria. We’d love to see your creations on Instagram, Facebook, and Twitter.
Recipe Testers’ Reviews
These mushroom burgers pack a lot of flavor. They are really, really delicious.
I’ve long been a fan of ramping up tomato flavors by using soy, vinegar, and sugar, and here it’s done to good effect. I let my tomato slices marinate for 4 hours. In the future, especially if I have a big beefsteak tomato where 1 slice covers the whole burger, I might even put the tomato slices on the grill for a few seconds per side. I didn’t do that with this recipe, but I’ve done it in the past and it can be lovely.
The mushrooms tasted great. This might sound crazy, but I recently put a portobello cap in my waffle iron and it came out amazingly good. So I think it could be fun to brush the caps with herb butter and then “waffle” them.
I used supermarket tomatoes for these. One of the supposedly more flavorful (and organic) varieties from Florida. It was okay because of the marinade. I used a fresno chile. I used Miyoko’s vegan butter. I used regular, mature spinach from my CSA. I cannot imagine that baby spinach would be as good here, let alone preferable.
I love portobello mushroom burgers, heirloom tomatoes, and herbs, all fresh from the garden. This mushroom burger hits all the high notes with layers of flavor that create a delicious, easy-to-assemble addition to the BBQ repertoire. You can easily have these on the table within an hour.
I marinated 2 sets of tomato slices—one batch for 30 minutes and another overnight. I decided 1 hour was enough to flavor the tomatoes.
I would have happily had 2 burgers except that I didn’t want 2 burger buns so I would compromise by serving crisp lettuce leaves as an optional alternative for buns.
I used yellow heirloom tomatoes, Thai red chile pepper, and Italian ciabatta buns.
Turns out we should have been marinating our burger tomatoes all along. These are so savory and summery! They also came together quickly. And while I did tweak my grilling process (I did stovetop and flipped the mushrooms to spread some butter onto the grill pan), the recipe is easy to follow, especially considering the lovely and tasty result.
I used local heirloom tomatoes, brown rice vinegar, ancho chile, and baby spinach. My tomatoes marinated for 45 minutes. My one addition would be to add a crisp leaf or two of romaine, just to give these a touch of crunch. Actually we got 2 servings as we both ate 2 burgers (heh) but you know, it depends on the crowd. We also didn’t have sides.
I grilled the burgers inside, on a cast-iron grill pan over a burner. This was the trickiest part of the recipe. The portobellos sat on the grill for approximately 10 minutes. And I will say, I just wasn’t sure about the whole “grill it butter-side-up” thing. The butter in my portobellos was solid by the time I put them on the grill (I melted my butter, stirred in the herbs, then poured it into the mushroom caps, where it cooled to a soft paste), and since my portobellos weren’t grilled in an oven or directly over hot coals, the butter didn’t really melt until I actually flipped them for a moment to transfer some butter onto the grill pan. I then flipped them back so they were still butter-side up for the majority. The buttery portobellos started to sizzle a bit after a minute, and once the bottom of each was lightly browned, I considered them done. I wonder if the recipe should say something like, brush the top of the mushroom with the butter mixture, then evenly distribute the rest of the butter between mushrooms… but then maybe you would need a slight bit more butter? And also the butter inside the mushrooms might still not melt. I don’t know, I thought flipping them worked out great. I would recommend it.
Originally published August 12, 2019
If you make this recipe, snap a photo and hashtag it #LeitesCulinaria. We'd love to see your creations on Instagram, Facebook, and Twitter.
“Wow. Really delicious.” That was his response after my partner inhaled his burger. And he was right. I don’t know what it is exactly that makes this so delicious, but I think it’s the combination of the marinated tomatoes, the garlicky spinach, and the roasted mushrooms. This vegan burger recipe is definitely a keeper!