80 gmbutter, coarsely chopped1Spanish onion, finely chopped3garlic cloves, finely chopped2 tbsp (loosely packed)each thyme, sage and rosemary, finely chopped400 gmmixed red and green grapes2 tbspplain flour, sieved1 tbspolive oil, plus extra to serveFor brushing:eggwash80 gmmarinated goat’s feta, drained6thin slices mild pancettaTo serve:vincotto12sage leavesRough puff pastry450 gm (3 cups)plain flour450 gmchilled butter, coarsely gratedWitlof salad120 gmcrème fraîche2 tbsplemon juice, or to taste1 tbspolive oil2 tbsp eachfinely chopped chives and flat-leaf parsley5witlof, bases removed, leaves separated
For rough puff pastry, sieve flour and 1 tsp fine salt onto a work surface. Scatter over butter and cut into flour with a pastry scraper until roughly mixed (there should still be small lumps of butter in the mixture). Make a well in the centre, add 180ml iced water and use pastry scraper to just combine. Bring dough together with the heel of your hand, then form into a disc. Wrap in plastic wrap and refrigerate until firm (20-30 minutes). Roll on a lightly floured surface to a 1.5cm-thick rectangle. Fold short ends together to meet in the centre then fold in half to form a book fold. Wrap in plastic wrap and refrigerate to rest (20 minutes). Repeat rolling and folding twice. Roll on a lightly floured surface to form a rough 15cm x 40cm rectangle, transfer to an oven tray lined with baking paper.
Meanwhile, preheat oven to 180C. Heat half the butter in a frying pan over low heat, add onion and garlic, sauté until tender (5-7 minutes). Add herbs, stir to combine, then set aside to cool. Combine grapes, flour, onion mixture and olive oil in a bowl, season to taste and scatter over pastry, leaving a 2cm border. Fold pastry edges over, brush with eggwash, then scatter over goat’s feta and bake until golden and cooked through (25-30 minutes).
Meanwhile, heat a large frying pan over high heat, add pancetta and turn occasionally until crisp (3-4 minutes). Drain on absorbent paper and set aside. Wipe pan with absorbent paper, heat remaining butter until foaming, add sage and fry until crisp (30 seconds-1 minute). Remove with a slotted spoon, drain on absorbent paper and set aside.
For witlof salad, whisk crème fraîche, lemon juice and olive oil in a bowl, season to taste, then stir through herbs. Drizzle over witlof.
Drizzle agrodolce grape tart with vincotto and olive oil, scatter with pancetta and sage, and serve with witlof salad to the side.