Pic of Portobello and pesto burgers with mozzarella, sweet potato wedges and kohlrabi slaw

Portobello and pesto burgers with mozzarella, sweet potato wedges and kohlrabi slaw

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Vegetarian mains

Portobello and pesto burgers with mozzarella, sweet potato wedges and kohlrabi slaw

Main Serves 2 40 min
Our virtuous take on a fast food classic. You also get to tackle one of our most misunderstood crops, the kohlrabi. Maybe it is the slightly alien appearance but it is one of our most queried veg, in terms of 'what is it?' and 'what do I do with it?'. It has a crisp, clean radish-like taste and can be used raw, as here, or cubed and roasted.


  • 600g sweet potatoes
  • olive oil
  • 200g Portobello mushrooms (3-4)
  • 2 tsp sweet smoked paprika
  • 1 large or 2 small carrots
  • ½ kohlrabi
  • 1 small red onion
  • 15g parsley
  • 50ml mayonnaise
  • 1 lemon
  • oil for roasting, sunflower or light olive
  • 1 Little Gem lettuce
  • 1 ball mozzarella
  • 3 tbsp green pesto
  • 2 bread rolls
  • salt and pepper


Prep time: 15 min
Cooking time: 25 min
  • Step 1

    Preheat oven to 200°C/Gas Mark 6. Wash the sweet potatoes and cut each one into 8 large wedges. Place them in the roasting tray with 2 tablespoons of oil. Season with salt and pepper. Dust with the paprika and mix well.
  • Step 2

    Spread out evenly and roast on the top shelf for 25 minutes until soft and coloured. Meanwhile, remove and discard the mushroom stalks. Pop the mushroom caps in a roasting tray, open side up. Season well with salt, pepper and plenty of oil.
  • Step 3

    Cover the tray with foil and put into the oven to roast for 15 minutes. While the potatoes and mushrooms cook, make your slaw. Wash and peel the carrot and kohlrabi. Grate the carrot(s) and kohlrabi on a coarse grater or slice them into thin matchsticks if you're feeling dexterous.
  • Step 4

    Peel and finely slice the onion. Wash the parsley and shake it dry. Pick the leaves and chop them finely. Mix the carrot, onion, kohlrabi and parsley with the mayonnaise.
  • Step 5

    Season the slaw with salt, pepper and a squeeze or 2 of lemon juice. Remove the mushrooms, uncover and put back in the oven to continue roasting for a further 5 minutes. Meanwhile, remove the root from the little gem to release the leaves.
  • Step 6

    Wash the leaves and pat dry with kitchen paper of a clean tea towel. Drain the mozzarella and tear it roughly into chunky pieces. When the mushrooms are ready, spoon some pesto into the open cavity of each and top with some mozzarella (you may not need to use it all).
  • Step 7

    Slide them back into the oven for a further 5 minutes. Pop the buns in the oven for a few minutes to warm them. Split the buns open and add a few crisp little gem leaves and a dollop of slaw. If you have 4 mushrooms, stack 2 in each bun.
  • Step 8

    If you have 3 mushrooms split one in half to equally divide them. Serve with the sweet potato wedges and remaining slaw.

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