Genevieve Taylor’s Portobello Mushrooms with Cannellini Beans, Mozzarella, Pesto & Breadcrumbs

Fire up the barbecue ready for direct cooking, adding a little smoking wood to the fire.
Toast the pine nuts in a small frying pan set over the fire. Transfer to a pestle and mortar and grind coarsely. Add most of the chopped basil (saving a sprinkle to garnish), the Parmesan and garlic and pound to a rough paste. Stir in the olive oil and vinegar and season to taste with salt and pepper.
Drizzle the mushrooms with olive oil, season well with salt and pepper, then rest them on the grill bars directly over the fire, gill-side down. The salt will draw a little moisture out of the mushrooms, which in turn will help the smoke to be sucked deep inside. Shut the lid and cook for 10 minutes, or until softening. Transfer, gill-side up, to a fireproof roasting tin and use a small sharp knife to ease out the cooked stems. Chop the stems and scatter into the hollows of the mushrooms.
Spoon the beans equally into the hollows of the mushrooms. Top each mushroom with 1–2 teaspoons of pesto and a slice of mozzarella. Sprinkle over the breadcrumbs and finish with a drizzle of olive oil, then slide the tin back over the fire. Shut the lid and cook for a further 10–15 minutes until the cheese is melting and the breadcrumbs are crisping up.
Serve hot and bubbling from the grill, sprinkled with the remaining basil, with crusty bread to mop up the juices, if you like.