Grilled fillet steak with the creamiest white beans & leeks

INGREDIENTS

• 4 leeks, trimmed and finely sliced
• 1 small bunch fresh thyme, leaves picked
• 2 cloves garlic, peeled and finely chopped
• olive oil
• 1 small wineglass white wine
• 500 g good-quality tinned butter beans, drained and rinsed
• 1 small handful freshly picked parsley leaves, finely chopped
• 1 tablespoon fat-free natural yoghurt
• good-quality peppery extra virgin olive oil
• sea salt
• freshly ground black pepper
• 4 x 200 g well-marbled quality fillet steaks, 2.5-4cm thick
• 1 lemon