Cajun Grilled Portobello & Guacamole Burger

Prep Time: 15 minutes
Cook Time: 20 minutes
Total Time: 35 minutes
Type: Vegan
Servings: 2
Spice Level: 🌶🌶 Medium
Estimated Cost: $16 - $20

Ingredients

For the Cajun Grilled Portobello:

• 2 large portobello mushroom caps, stems and gills removed

• 3 tablespoons extra virgin olive oil

• 2 tablespoons balsamic vinegar

• 1½ teaspoons Cajun seasoning

• 1 teaspoon smoked paprika

• 1 teaspoon garlic powder

• ½ teaspoon black pepper

• Pinch of sea salt

For the Guacamole:

• 2 ripe avocados

• 1 tablespoon fresh lime juice

• 1 small garlic clove, minced

• 2 tablespoons fresh cilantro, finely chopped

• ½ teaspoon sea salt

• Pinch of black pepper
  

For the Crispy Fried Green Tomato:

• 2 firm green tomatoes, sliced into ½ inch rounds

• ½ cup cornmeal

• ¼ cup all-purpose flour

• 1 teaspoon Cajun seasoning

• ½ teaspoon smoked paprika

• ½ teaspoon garlic powder

• Pinch of sea salt

• Neutral oil for frying (avocado or sunflower)

For the Creole Mustard Aioli:

• ¼ cup vegan mayonnaise

• 1 tablespoon Creole mustard

• 1 teaspoon fresh lemon juice

• ½ teaspoon smoked paprika

• ½ teaspoon garlic powder

• Pinch of black pepper

For the Assembly:

• 2 brioche buns, sliced and toasted

• 2 slices vegan smoked gouda

• Fresh arugula for layering

• Lime wedges for serving

Substitutions

• Brioche bun: A toasted potato bun delivers a slightly softer, lighter alternative that holds up well to the fillings.

• Vegan smoked gouda: Vegan pepper jack adds extra heat and melts beautifully as an alternative.

• Creole mustard: Whole grain Dijon mustard delivers a similar texture and tang as a substitute.

• All-purpose flour in the coating: Chickpea flour works as a gluten-free alternative with a slightly nuttier flavor.

• Fresh arugula: Baby spinach or shredded romaine lettuce substitutes well for a milder green layer.

Instructions

1. Remove stems and gills from portobello caps using a spoon. Whisk olive oil, balsamic vinegar, Cajun seasoning, smoked paprika, garlic powder, black pepper, and sea salt together in a shallow bowl. Place portobello caps gill-side down in the marinade and let sit for at least 10 minutes, flipping once halfway through.

2. While portobellos marinate, mash avocados in a bowl until chunky and textured. Fold in lime juice, minced garlic, fresh cilantro, sea salt, and black pepper. Taste and adjust seasoning. Cover with plastic wrap pressed directly against the surface and set aside.

3. Whisk vegan mayonnaise, Creole mustard, lemon juice, smoked paprika, garlic powder, and black pepper together in a small bowl until smooth. Refrigerate until ready to assemble.

4. Combine cornmeal, flour, Cajun seasoning, smoked paprika, garlic powder, and sea salt in a shallow bowl. Press green tomato rounds firmly into the cornmeal mixture, coating both sides evenly.

5. Heat about ½ inch of neutral oil in a skillet over medium-high heat. Fry coated green tomato rounds for 2 - 3 minutes per side until deeply golden and crispy. Transfer to a paper towel-lined plate and season immediately with a pinch of sea salt.

6. Heat grill or grill pan over medium-high heat. Lightly brush grill grates with oil. Place marinated portobello caps gill-side up and grill for 4 - 5 minutes per side until deeply caramelized with visible char marks and tender throughout.

7. Place one slice of vegan smoked gouda on each portobello cap during the final minute of grilling. Cover loosely with a lid or foil to melt the cheese.

8. Toast brioche buns cut-side down in a dry skillet or under the broiler for 1 - 2 minutes until golden.

9. Spread Creole mustard aioli generously on both sides of each toasted brioche bun.

10. Layer fresh arugula on the bottom bun. Place the grilled portobello cap with melted gouda on top of the arugula. Stack the crispy fried green tomato on top of the portobello. Spoon chunky guacamole generously over the fried green tomato. Cap with the top brioche bun.

Love at First Bite

That first bite announces itself. The char on the grilled portobello hits first - smoky, deep, and savory - then the crispy fried green tomato cracks through with a bright, tangy punch, then the cool chunky guacamole rolls in with its lime and cilantro freshness, and the Creole mustard aioli ties every layer together with a bold, slightly spicy finish. The toasted brioche bun holds it all with a light, buttery embrace that never gets in the way.

Origin Story

Portobello mushrooms became a plant-based staple precisely because they deliver what great meat-based burgers promise - a meaty, juicy, deeply satisfying bite that holds up to bold seasoning and high heat. Soul Foodie seasons the portobello with Cajun spice, a seasoning tradition rooted in the rich African, French, and Caribbean culinary heritage of Louisiana, then grills it until those char marks tell the whole story. The fried green tomato brings pure Southern soul food tradition to the stack - a beloved staple of African American Southern cooking that deserves its place at the center of the plate. Together, these ingredients build a burger that feels like home and tastes like celebration.

Remix Notes

Add a few bread and butter pickle slices beneath the arugula for a sweet, tangy layer that plays beautifully against the Cajun spice and Creole aioli. A light drizzle of hot sauce over the guacamole before capping the burger adds welcome heat for spice lovers. Swap the fried green tomato for a thick slice of grilled pineapple for a Caribbean-inspired variation that shifts the whole flavor profile in a bold, unexpected direction.

Soul Notes

Removing the gills from the portobello cap before marinating makes a meaningful difference. The gills hold excess moisture that releases during grilling and can make the burger wet and heavy. A spoon removes them cleanly in seconds. Marinating gill-side down lets the portobello absorb the Cajun and balsamic flavors from the inside out - delivering a deeply seasoned, caramelized result that tastes like it came off a proper Southern grill.

Pairs Well With

This burger pairs beautifully with a cold glass of sweet tea with fresh peach, a side of Cajun roasted corn on the cob, or a crispy kale and roasted sweet potato salad. Each pairing keeps the Southern soul food energy alive without competing with the bold flavors of the burger.

• Cajun Roasted Corn on the Cob

• Crispy Kale & Roasted Sweet Potato Salad

• Sweet Tea with Fresh Peach

Storage & Reheating

Store all components separately in airtight containers in the refrigerator for up to two days. Reheat the grilled portobello cap in a skillet over medium heat for 3 - 4 minutes or on the grill for 2 minutes per side. Re-crisp fried green tomato rounds in a dry skillet or air fryer for 1 - 2 minutes. Keep guacamole covered with plastic wrap pressed directly against the surface to prevent browning. Assemble fresh each time for the best texture and experience.

FAQ

Can I cook the portobello in a skillet if I don't have a grill?
Yes. A cast iron grill pan over medium-high heat delivers excellent char marks and caramelization indoors. A regular cast iron skillet works equally well and delivers a deeply seared, flavorful result.

My fried green tomatoes keep losing their coating in the oil - what am I doing wrong?
Pressing the coating firmly onto both sides of each tomato slice and letting them rest for 2 minutes before frying helps the coating adhere. Oil temperature matters too - if the oil isn't hot enough, the coating absorbs oil and slides off before it crisps.

How do I keep the guacamole from browning before serving?
Press plastic wrap directly against the surface of the guacamole with no air gaps. The lime juice in the recipe also slows browning significantly. Make it as close to serving time as possible for the freshest color and flavor.

Related Recipes You'll Love