Portobello Umami Burgers

This one's for the vegetarians at your cookout — and honestly, it'll have the meat-eaters sneaking one too. Portobello mushrooms are the secret weapon here: meaty, substantial, and packed with natural umami that holds up brilliantly over charcoal. No crumbling, no squishing, no sad veggie afterthought. Just a proper burger that earns its place on the grill.

Ingredients

• 4 large portobello mushrooms, stalks trimmed
• 4 tablespoons (60ml) olive oil
• 3 tablespoons (45ml) soy sauce
• 2 tablespoons (30ml) balsamic vinegar
• 2 cloves garlic, finely minced
• 1 teaspoon (5ml) Worcestershire sauce
• 1 teaspoon smoked paprika
• ½ teaspoon freshly ground black pepper
• 4 slices provolone or mature cheddar
• 4 burger buns, lightly toasted on the grill
• Handful of rocket
• 1 large beef tomato, sliced
• ½ red onion, thinly sliced
• Mayonnaise or aioli, to serve

Method

1. Whisk together the olive oil, soy sauce, balsamic vinegar, garlic, Worcestershire sauce, smoked paprika, and black pepper in a bowl to make the marinade.
2. Place the portobello mushrooms gill-side up in a shallow dish and spoon the marinade generously over them, making sure the gills soak it up. Leave to marinate for at least 20 minutes at room temperature, or up to 2 hours in the fridge.
3. Set up your BBQ for direct grilling over medium-high heat — aim for around 200–220°C at grate level. Give the grates a good brush and oil them lightly to prevent sticking.
4. Place the mushrooms gill-side down on the grill. Cook for 4–5 minutes until the top side starts to look dry and the mushroom begins to soften.
5. Flip the mushrooms and cook for a further 3–4 minutes gill-side up. The mushrooms should be tender throughout and slightly shrunken — that's the moisture cooking off and the flavour concentrating. Good sign.
6. In the last minute of cooking, lay a slice of cheese over each mushroom and close the lid briefly to let it melt.
7. While the mushrooms finish, toast the cut sides of your buns on the grill for 1–2 minutes until lightly golden.
8. Build your burgers: spread aioli or mayonnaise on the base, add rocket, a slice of tomato, the cheesy portobello, and a few rings of red onion. Crown with the top bun and serve straight away.

Originally published by Bull BBQ. Adapted for UK audiences by Cedar Kitchen in the Garden.