BBQ Portobello burger with Romesco

Ingredients for 4 people

For the portobello burgers

• 4 large portobellos of similar size
• 4 sturdy burger buns
• 2 roasted red bell peppers, grilled yourself or according to label
• arugula to taste
• 4–6 tablespoons romesco
• 2 tablespoons oil
• lemon juice or mild vinegar
• BBQ rub to taste
• optional: cheese or a plant-based alternative

For the complete meal

• 1 portion BBQ-style potato salad
• optional: extra grilled vegetables

Allergens and variations

• Buns often contain gluten and may contain sesame, milk, egg, or soy.
• Romesco may contain nuts and bread, depending on the recipe.
• Cheese contains milk.
• Use certified gluten-free buns and a gluten-free romesco for a gluten-free version.
• Use vegan buns, romesco, and toppings for a vegan version.
• Always check the current labels and prevent cross-contamination when necessary.

Which portobello to choose?

Choose firm portobellos with an intact cap and no slimy spots. The diameter should approximately match the bun. Larger specimens lose moisture during grilling and shrink slightly. Store and use them according to the packaging and current food safety guidelines.

Cleaning portobellos

1. Gently wipe away visible dirt with a soft brush or cloth.
2. Remove only the hard end of the stem, or twist the stem out if it fits better on the bun.
3. Avoid long soaking; mushrooms absorb moisture.
4. Pat the surface dry before applying oil and spices.

Should you remove the gills?

No, you don't have to. The dark gills are edible and provide flavor. You can remove them carefully if you want a lighter-colored sauce or a neater presentation, but it is not a requirement.

Seasoning portobellos

1. Mix oil with a small amount of lemon juice or vinegar.
2. Brush the portobellos thinly, including the edges.
3. Apply rub according to the current packaging.
4. Do not leave the mushrooms unrefrigerated for longer than necessary.

Do not use too much oil or salt: portobellos release their own moisture during grilling, and strong seasoning can overpower the earthy flavor.

Preparing the BBQ

1. Create a direct zone and a cooler zone.
2. Preheat the grate in a controlled manner and clean it.
3. Keep tongs or a wide spatula ready.
4. Only prepare buns and toppings just before serving.

Read more about the two-zone setup and direct and indirect heat.

Grilling portobellos

1. Place the portobellos over controlled direct heat.
2. Allow one side to develop color and grill marks without constantly turning.
3. Turn carefully and let the other side cook.
4. Move to the cooler zone if the outside gets dark too quickly.
5. Let excess moisture drain carefully before placing the mushroom on the bun.
6. Add cheese only at the end and, if necessary, briefly close the lid, following your BBQ's safe operating instructions.

The exact cooking time depends on size, moisture content, and BBQ heat. The portobello is ready when it is supple and heated through, but still has enough structure to serve as a burger.

Toasting the buns

1. Cut the buns open.
2. Toast the cut surfaces briefly over controlled heat.
3. Remove them as soon as they are lightly crispy; bread burns quickly.

A toasted cut surface slows down the absorption of moisture from the portobello and sauce.

Assembling the portobello burger

1. Spread romesco on the bottom buns.
2. Add arugula and grilled bell pepper.
3. Place the grilled portobello on top.
4. Add optional cheese or extra sauce.
5. Close with the top bun and serve immediately.

Romesco as burger sauce

Romesco combines roasted bell pepper with a rich, slightly smoky flavor. Check for nuts and gluten when using a jarred sauce or your own recipe. Make the sauce in advance and store it chilled according to the recipe.

View the full romesco recipe and the BBQ sauce encyclopedia.

Which rub suits portobello?

• Toscana Fire for fennel and Italian spiciness;
• Shawarma BBQ Dry Rub with tahini or hummus;
• Smoky Spicy Tex-Mex BBQ Rub with salsa and avocado;
• Korean BBQ Rub with cucumber and a suitable sauce.

Check packaging, ingredients, allergens, and dosage. The chosen rub can determine whether the dish remains vegan or gluten-free.

Preventing portobello from sticking

• Clean the grate and preheat it in a controlled manner.
• Pat the mushroom dry and brush it thinly with oil.
• Let color develop before turning.
• Use a wide spatula if the cap is fragile.
• Choose a plancha or grill basket if using smaller mushrooms.

Also read food sticking to the BBQ grate.

Make it a complete meal

Serve one burger per person with potato salad, grilled corn, or a legume salad. This adds bulk and more nutritional variety in addition to the portobello. Adjust the quantities based on appetite and the number of courses.

• BBQ-style potato salad
• Corn on the BBQ
• Tabbouleh
• Hummus

Other toppings

• chimichurri and grilled onion;
• tahini, cucumber, and pickled onion;
• hummus and grilled eggplant;
• salsa, avocado, and corn;
• cheese, arugula, and mustard sauce.

See chimichurri and tahini sauce.

Storing leftovers

Store grilled portobello, buns, sauce, and salad separately. Chill leftovers promptly and follow local storage guidelines. Assemble burgers just before eating to prevent soggy buns.

More vegetarian BBQ recipes

• Tofu and tempeh skewers
• Vegetarian BBQ hub
• Eggplant on the BBQ
• Cauliflower on the BBQ
• Using rub on vegetables
• All BBQ recipes

Frequently asked questions

How long should a portobello be on the BBQ?

That depends on size, moisture, and heat. Grill until the portobello is heated through and supple, but still has structure.

Do you have to remove the gills?

No. The gills are edible. Removing them is only a choice for presentation or a lighter result.

How do you prevent a soggy bun?

Toast the cut surface, let excess moisture drain from the portobello, and assemble the burger just before serving.

Is a portobello burger vegan?

It can be. Use vegan buns, sauce, and toppings, and leave out dairy cheese.

How do you make it gluten-free?

Use a certified gluten-free bun and check the romesco, rub, and toppings for gluten and cross-contamination.