4 large Portobello mushrooms
4 tbsp olive oil
salt and ground black pepper
2 beefsteak tomatoes, sliced
4 slices halloumi cheese
4 burger buns
1 small red onion, thinly sliced
For the tarragon butter
50g/2oz/4 tbsp butter, softened
1 garlic clove, crushed
2 tbsp chopped fresh tarragon
1 To make the tarragon butter, place the butter, garlic and tarragon in a bowl, season with salt and pepper and blend.
2 Brush the mushrooms with olive oil and season with salt and pepper. Grill (broil) for 5 minutes, until softened. Remove and keep warm. Place the tomato slices under the grill (broiler)
and cook for 1 minute to warm them through.
3 Cook the halloumi on a hot griddle pan for 2 minutes each side, until golden and softened.
4 Split the burger buns and spread thickly with the tarragon butter. Layer the red onion rings, mushrooms, tomatoes and halloumi on the bottom half of each bun. Cover with the top halves and serve.