- 400 g beef mince
- 1 egg
- 2 tbs finely chopped flat-leaf parsley leaves
- 2 tsp dried rosemary
- 1 tsp dried chilli flakes
- Sea salt and freshly ground black pepper
- 1 tomato
- 4 large unsweetened gherkins
- 1 baby gem lettuce
- 2 tbs coconut oil, grass-fed butter or ghee, plus extra as needed
- 1 red onion, sliced into rings
- 8 large portobello mushrooms
Add the mince, egg, parsley, rosemary and chilli to a large bowl. Season with salt and pepper and, using your hands, mix everything together really well. Shape into four equal-sized balls, then gently flatten them to form 3 cm thick patties. Place on a plate or tray and transfer to the fridge for 10 minutes to firm up.
While the patties are firming, prepare your toppings. Finely slice the tomato and gherkins. Separate the lettuce into single leaves and set aside until needed.
Remove the patties from the fridge and leave for about 10 minutes to come back to room temperature.
Melt your preferred cooking fat in a large frying pan over medium–high heat. Add the patties and cook for 2–3 minutes each side, or until golden brown and cooked through. Transfer to a plate, cover loosely with foil and set aside to rest.
Add a little more cooking fat to the pan, together with half the onion and mushrooms, stem-side down. Cook for 4–6 minutes, turning the mushrooms halfway through cooking, or until the onion has softened and caramelised and the mushrooms are soft and tender. Transfer to a plate and repeat with the remaining onion and mushrooms.
To plate up, start with a mushroom stem-side up on the plate, then layer over a few lettuce leaves followed by one of the burger patties, some tomato and gherkin slices and some of the caramelised onion. Top the whole thing off with another mushroom, stem-side down. Repeat with the rest of the ingredients and dig in!