For the lamb heat a heavy-based frying pan over medium-high heat until hot. Season the lamb with salt and pepper and then sear quickly on each side. Transfer to a warm plate. Pound the sage, thyme garlic and olive oil to a thick paste, using a pestle and mortar. Smear this over the lamb fillets. Put the lamb fillets into a 200°C oven for 6 minutes.
Put the beans, red onion, garlic, thyme, tomatoes and parsley in a pan with the olive oil. Place over medium heat and simmer for 3-4 minutes, stirring, to heat through. Add a splash of balsamic vinegar, red wine and a squeeze of lemon juice. Season with salt and freshly ground black pepper. Set aside and keep warm.
Meanwhile make the chutney. Cook the finely shredded leeks in olive oil for a few minutes, then add the balsamic vinegar and brown sugar. Cook for five minutes on a medium-low heat.
Reduce the heat to medium-low. Add a large glug of balsamic vinegar to the pan. Sizzle for a few seconds, scraping up any sediment from the pan. Season with salt and pepper then add to the chutney mixture. To serve, spoon the bean mixture onto warm serving plates. Place the lamb on top and drizzle on the hot leek chutney.