Portobello mushrooms with roasted garlic mayo on potato sourdough

Roasting mushrooms really brings out their earthy flavour, providing a satisfying alternative to meat for vegetarians. We serve them on a thickly crusted, chewy sourdough made with potatoes, which provides a good contrast to their soft texture. If you don’t have time to make the Roasted Garlic Mayonnaise, simply crush a quarter of a garlic clove and stir it into some mayo or, even easier, rub the toast with a cut garlic clove instead.