Place a large piece of parchment onto a large baking sheet
Half the leeks lengthwise and wash gently
Arrange leek halves snuggly cut side down on parchment paper into three pairs, alternating green and white ends for balance
Draw around each set of leeks with a pencil and set the leeks to one side
Within the stencil lines, drizzle olive oil and honey
Generously sprinkle sea salt and black pepper
Place sage leaves into the stencils along with an even sprinkling of lemon
Lay the leek halves back on top and spread sour cream over them evenly
Season again with more oil, honey, salt and pepper
Roll out puff pastry on a lightly floured surface
Cut the pastry rectangle into three pieces and roll each out at least 4 cm long and wider than each set of leeks
Using a rolling pin, lift each rectangle of pastry carefully and lay on top of each set of leeks
Bake in a hot oven for 35 minutes until the pastry has risen and is dark golden brown
Allow to rest for five minutes
Flip the tart upside down onto a chopping board and serve
