Step 1

Preheat the oven to 392F / 200CBrush both sides of the mushrooms with the oil then with the balsamic vinegar. Season with salt and pepper.Place the mushrooms stem side up on a small baking tray.Bake in the oven for 10 to 15 minutes.

Step 2

Split the ciabattas in half, brush a little oil over each one then toast the inside of both pieces on a hot griddle pan. In a small bowl mix the pesto and the mayo together.Spread the mayo over the bottom ciabatta.

Step 3

When the mushrooms are roasted, carefully pat them dry if they are very wet.Place one mushroom on each ciabatta. Crumble over the feta then add the tomatoes and a couple of basil leaves.Place the remaining ciabatta on top on then serve immediately.