Picnic loaf

Method

1. Preheat the grill to high. Put the vegetables into a large bowl, drizzle with 4 tablespoons olive oil and season to taste. Toss together, then lay half in a single layer on a wire rack resting on a baking tray. Place directly under the hot grill and cook for 4-5 minutes each side or until just tender and lightly charred. Set aside in a bowl. Repeat with the remaining vegetables.
2. Mix the remaining oil, vinegar and garlic and toss through the vegetables with half the basil leaves and some seasoning. Leave to marinate for 2 hours, stirring halfway. (Angela Hartnett’s tip: Leave out any vegetable you don’t like and up the quantity of another in its place. You could also add anchovies.)
3. Cut the top third off the loaf to create a lid and base. Using your fingers, scoop out the soft bread from the base, leaving a 2-3cm shell near the crust – it’s important the shell isn’t too thin, otherwise it won’t stay crisp once filled. Repeat with the lid. (Angela Hartnett’s tip: Whizz up the soft bread from inside the loaf to make breadcrumbs and freeze to use another time.)
4. Using a spoon, spread 2 tablespoons of the tapenade in the base of the hollowed-out bread. Spread the rest in the lid.
5. Slice the mozzarella and pat dry with kitchen paper. Tip the drained vegetables onto plenty of kitchen paper and also pat dry thoroughly – this is really important, as wet vegetables will cause the bread shell to turn soggy. Start layering the mozzarella and vegetables (except the mushrooms) in the base, seasoning and scattering with the remaining basil leaves, freshly torn, as you go. Slice the mushrooms, pat dry with kitchen paper and lay them in the lid.
6. Put the lid back on the loaf and wrap well in cling film. Transfer to a baking tray and place another tray on top. Weigh down with a few full jars or cans of vegetables – about 1kg in total. Set aside in a cool place for 2 hours to compress slightly. Unwrap the loaf and cut into thick slices to serve.