Recipe: Make our ultimate mushroom burger

Make our delicious stacked mushroom burger with sticky onion relish, olive and potato rosti and grilled halloumi.

One of the saddest things, I think, about summer barbecues is the vegetarian options. If there's one time of year it must suck to be veggie or vegan, this is it. Because, honestly, there's nothing more disappointing than a flaccid defrosted supermarket wheat protein sausage. For one, they almost always fall apart (with half tumbling onto the meat side of the grill). Secondly, they burn so easily it's as if they've been pre-coated in petroleum. And most of them taste revolting!

I've got several vegetarian friends so always try to make extra special effort when they come over – although they'd be pretty happy with a box of Linda McCartneys and a few slices of grilled halloumi.

The go-to vegetarian alternative for barbecues has to be mushrooms. If you treat them right, they can even beat a decent burger in the taste stakes. Cooked slowly they take on an almost meaty flavour and texture.

Here I have taken the 'mushroom burger' to the next level. After being marinated in nice things, the mushrooms are baked and finished on the barbecue, served with a crispy olive and potato rosti and sweet and sticky tomato and onion relish. Oh, and there's halloumi too.

What more could you possibly need?

I used local mushrooms organically grown in Capel St Mary, and potatoes from Fairfields Farm.

The ultimate mushroom burger

(makes 2)

Ingredients

2 Portobello mushrooms

1tbsp oil

2tbsps each soy sauce and lemon juice

1 clove crushed garlic

For the rostis

250g grated new potatoes

1tbsp olives finely chopped

Handful fresh parsley finely chopped

1 egg

Seasoning

1tbsp flour

Oil for frying

For the relish

6 small tomatoes chopped roughly

1 onion finely sliced

1tbsp each balsamic vinegar and caster sugar

Seasoning

1tbsp butter

Halloumi and crusty rolls to serve

Method

Peel the outer layer of the mushrooms away so the marinade will soak in nicely. Combine in a bowl with the marinade ingredients. Leave for 30 minutes then cover and bake at 190C for 30 minutes and set aside.

For the rostis squeeze out the excess juice from the potatoes and add the rest of the ingredients. Heat oil in a frying pan and place just over 1tbsp of mixture into it in piles. Cook on a medium heat for one minute then turn over to crisp the other side. Set aside.

Make the relish by frying all the ingredients together until soft and caramelised.

To compose, place the mushrooms, halloumi and rostis on a barbecue. Once the halloumi is coloured pile into the buns with some of the relish.

Alternatively finish the rostis, halloumi and mushrooms under the grill.